Eddy current sensors are versatile and widely used in various industrial applications due to their ability to measure displacement, position, and other parameters of electrically conductive materials in harsh environments. These sensors leverage the principles of electromagnetic induction to provide reliable and non-contact measurements, making them invaluable tools in diverse industries.
Displacement and Position Measurement
Eddy current sensors excel at measuring the displacement and position of electrically conductive targets with high accuracy and resolution. The working principle of an eddy current sensor is based on the generation of eddy currents in the target material, which in turn create a magnetic field that opposes the primary magnetic field of the sensor coil. The change in the sensor’s impedance, caused by the interaction between the primary and secondary magnetic fields, is used to determine the distance between the sensor and the target.
Eddy current sensors can measure both ferromagnetic and non-ferromagnetic materials, with a typical measurement range of up to several millimeters. The sensor’s ability to operate without physical contact with the target allows for precise and wear-free measurements, making them ideal for applications such as:
Monitoring the position of machine parts, such as pistons, valves, and bearings
Measuring the displacement of rotating shafts and spindles
Detecting the position of metallic components in industrial automation and control systems
The high-frequency operation of eddy current sensors enables them to provide fast and accurate measurements, even in dynamic environments with high speeds and accelerations.
Harsh Industrial Environments
One of the key advantages of eddy current sensors is their superior tolerance for harsh industrial environments. These sensors are designed to withstand exposure to various contaminants, such as oil, dirt, dust, and moisture, without compromising their performance. Additionally, they are highly resistant to magnetic interference fields, making them suitable for use in applications where strong electromagnetic fields are present.
Eddy current sensors can operate reliably in a wide range of temperatures, pressures, and speeds, making them suitable for use in the following industries:
Oil and gas: Monitoring the condition of drilling equipment, pipelines, and other critical components
Automotive: Measuring the position and wear of engine components, such as camshafts and crankshafts
Aerospace: Monitoring the condition of aircraft components, such as landing gear and turbine blades
The robust design and environmental resilience of eddy current sensors ensure reliable and consistent measurements, even in the most demanding industrial settings.
Non-Destructive Testing
Eddy current testing is a widely used non-destructive testing (NDT) technique for inspecting electrically conductive materials. This technique involves inducing eddy currents in the test material and analyzing the changes in the sensor’s impedance to detect defects, such as cracks, corrosion, and other flaws.
Eddy current NDT offers several advantages over other inspection methods:
High-Speed Inspection: Eddy current sensors can perform inspections at very high speeds, making them suitable for high-volume production environments.
No Contact Required: Eddy current testing does not require any physical contact between the sensor and the test piece, eliminating the risk of damage to the material.
Versatility: Eddy current NDT can be used to inspect a wide range of conductive materials, including metals, alloys, and some non-metallic materials.
Reliable Quality Control: Eddy current testing can provide reliable and consistent quality control systems for the metal industry, ensuring the integrity of critical components and structures.
By leveraging the unique properties of eddy currents, these sensors can detect and characterize defects in materials with high accuracy and efficiency, making them an invaluable tool for quality assurance and process control.
Thin Film Measurement
Eddy current sensors can also be used to measure the electrical conductivity of thin films of metals. This application is particularly relevant in the semiconductor and electronics industries, where the precise characterization of thin conductive layers is crucial for device performance and reliability.
Subminiature eddy-current transducers (ECTs) can be used to study the electrical conductivity of thin films of metals by analyzing the amplitude of the eddy-current transducer signal. This non-contact measurement technique allows for the evaluation of thin film properties without the need for physical contact, which can potentially damage the delicate structures.
The ability to measure thin film conductivity using eddy current sensors enables researchers and engineers to:
Optimize the deposition and processing of thin metal films
Detect defects and irregularities in thin film coatings
Monitor the thickness and uniformity of conductive layers
By providing a reliable and non-invasive method for thin film characterization, eddy current sensors contribute to the advancement of semiconductor and electronics technologies.
Material Properties Determination
In addition to displacement, position, and thin film measurement, eddy current sensors can also be used to determine various material properties, such as conductivity, permeability, and thickness.
Conductivity Measurement: Eddy current sensors can be used to measure the electrical conductivity of conductive materials. The sensor’s response is directly related to the material’s conductivity, allowing for the evaluation of material composition and quality.
Permeability Measurement: Eddy current sensors can also be used to measure the magnetic permeability of ferromagnetic materials. This information is crucial for applications involving magnetic materials, such as the monitoring of transformer cores and the detection of defects in steel structures.
Thickness Measurement: Eddy current sensors can be used to measure the thickness of thin materials, conductive coatings, and non-conductive coatings on conductive substrates. This capability is valuable for quality control, process monitoring, and the detection of wear or corrosion in various industrial applications.
By leveraging the unique properties of eddy currents, these sensors can provide valuable insights into the physical and electrical characteristics of materials, enabling more informed decision-making and process optimization.
Conclusion
Eddy current sensors are versatile and widely used in various industrial applications due to their ability to measure displacement, position, and other parameters of electrically conductive materials in harsh environments. These sensors offer a range of advantages, including high-speed and non-contact measurement, superior tolerance for harsh conditions, and the ability to determine material properties.
As technology continues to advance, eddy current sensors are becoming more miniature, low-cost, and high-speed, making them suitable for a wide range of high-volume OEM applications. By understanding the principles and capabilities of eddy current sensors, engineers and scientists can leverage these powerful tools to drive innovation and improve the performance and reliability of their systems.
References
Bestech Australia. (n.d.). Eddy Current Sensor Principle. Retrieved from https://www.bestech.com.au/blogs/eddy-current-sensor-principle/
National Center for Biotechnology Information. (2012). Eddy Current Sensor for Displacement Measurement. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3231639/
IOP Publishing. (2018). Eddy Current Sensor for Thin Film Conductivity Measurement. Retrieved from https://iopscience.iop.org/article/10.1088/1757-899X/441/1/012029
United States Air Force. (n.d.). Eddy Current Testing. Retrieved from https://content.ndtsupply.com/media/Eddy%20Current%20-USAF-Tech-Manual-N-R.pdf
A lensometer is an essential optical instrument used to measure the dioptric vertex power, optical center, cylindrical axis, and prism of a lens. It plays a crucial role in establishing and verifying a reference refractive prescription before an eye examination. The process of measuring the prescription of a refractive lens, where the lensometer compensates with a focal length that neutralizes the lens, is known as “neutralization.”
History of Lensometry
The history of lensometry dates back to the mid-19th century, with the development of the photographometer by Antoine Francois Jean Claudet in 1848. The first focimeter was introduced in 1912 by Troppman, and modern lensometers are derived from these past advances.
Types of Lensometers
There are two main types of lensometers: manual and automated.
Manual Lensometers
Manual lensometers use a battery-powered, LED illumination system to measure the precise powers of the sphere, cylinder, axis, add, and prism of a lens manually. The two most common types of manual lensometer are the American Cross and European Dot.
American Cross Lensometer
The American cross lensometer consists of a series of uniform lines located at right angles to one another. The triple thin lines are designated as the “sphere lines,” and the single thick line is the “cylinder line.”
European Dot Lensometer
The European dot lensometer consists of a series of uniform dots located at right angles to one another. A protractor grid is used to determine the cylinder axis.
Automated Lensometers
Automated lensometers are automatic instruments that measure repeatable, fast, and reliable lens prescriptions. They employ a white light and ray-trace system to measure the powers of the sphere, cylinder, axis, add, and prism of a lens in a single operation. The values of each measure are then displayed digitally and can be printed or recorded manually.
Lens Types Neutralized by Lensometers
A lensometer can neutralize various types of lenses, including:
Single-vision lenses
Bifocal lenses
Trifocal lenses
Progressive lenses
Prismatic lenses
Rigid gas-permeable lenses
These lenses contain four primary types of powers:
Spherical power
Cylindrical power
Additions for near vision
Prismatic power
Measurable Data from Lensometers
A lensometer can measure the following quantifiable data:
Dioptric Vertex Power: The power of a lens measured at the vertex, or the point where the lens is closest to the eye.
Optical Center: The point on the lens where the light rays pass through without any deviation.
Cylindrical Axis: The orientation of the cylindrical power of the lens, measured in degrees.
Prism: The amount of prismatic power in the lens, measured in prism diopters.
American Cross Lensometer Measurements
The American cross lensometer consists of a series of uniform lines located at right angles to one another. The triple thin lines are designated as the “sphere lines,” and the single thick line is the “cylinder line.” The intersection of these lines indicates the optical center of the lens.
European Dot Lensometer Measurements
The European dot lensometer consists of a series of uniform dots located at right angles to one another. A protractor grid is used to determine the cylinder axis, which is the orientation of the cylindrical power of the lens, measured in degrees.
Lensometer Parts and Components
A typical lensometer consists of the following parts and components:
Illumination System: The illumination system is responsible for providing the light source used to measure the lens. This can be a battery-powered, LED-based system in manual lensometers or a white light source in automated lensometers.
Lens Holder: The lens holder is the part of the lensometer where the lens to be measured is placed. It is designed to securely hold the lens in a specific orientation.
Reticle: The reticle is the pattern of lines or dots (depending on the lensometer type) that is projected onto the lens being measured. This pattern is used to determine the various lens parameters.
Focusing Mechanism: The focusing mechanism allows the user to adjust the distance between the lens and the reticle, enabling the lensometer to accurately measure the lens power.
Measurement Scales: The measurement scales, typically located on the lensometer, are used to read and record the various lens parameters, such as sphere, cylinder, axis, and prism.
Digital Display: Automated lensometers often feature a digital display that shows the measured lens parameters, making it easier to record the data.
Printer Interface: Some lensometers may have a printer interface, allowing the measured lens data to be printed for record-keeping or patient records.
Calibration Mechanism: Lensometers require periodic calibration to ensure accurate measurements. The calibration mechanism, which may include test lenses or other calibration tools, is used to verify and adjust the lensometer’s performance.
Conclusion
A lensometer is a crucial optical instrument used to measure the dioptric vertex power, optical center, cylindrical axis, and prism of a lens. It plays a vital role in establishing and verifying a reference refractive prescription before an eye examination. Understanding the history, types, lens neutralization capabilities, measurable data, and the various parts and components of a lensometer is essential for anyone working in the field of optics and vision care.
References
Lensometry – StatPearls – NCBI Bookshelf
Lensometry – EyeWiki
Lensometers | PPT – SlideShare
The focimeter— measuring the power of eyeglass lenses
A reflecting telescope is developed based on the principle of light reflection by a mirror or a combination of curved mirrors to generate an image. These telescopes come in different design variations and also includes additional optical elements at times for enhancing the image quality or mechanically improve the position of the image. Since reflecting telescopes/reflectors involve mirrors, they are termed as “catoptric” telescopes. These telescopes are commonly used for astronomical purposes. Prominent telescopes like the Hubble Space Telescope and some amateur telescopes are based on this microscopic design. Additionally, telescopes that operate with wavelengths of light other than the visible range (such as X-RAY telescopes) also use the principle of reflecting telescopes.
Who invented the reflecting telescope?
The use of parabolic mirrors in such telescopes has reduced spherical aberration leading to several telescopic designs following the reflection principle. One of the most important telescopic designs was the Gregorian telescope proposed by James Gregory in 1663 and was built by experimental scientist Robert Hooke in 1673.
Sir Isaac Newton is considered to be the creator of the first reflecting telescope in 1668. This design is referred to as the Newtonian telescope. The Newtonian telescope uses a spherical-ground metal primary mirror and a small diagonal-mirror.
In the late 20th century, the field of adaptive optics and lucky imaging has witnessed a development helping to overcome the difficulties of seeing. Now, reflecting telescopes have become omnipresent on space telescopes and several other types of spacecraft imaging devices.
How does a reflecting telescope work?
Path of light in a reflecting telescope.
The reflector telescope has a curved primary mirror as its fundamental optical element. This mirror is used for creating an image at the focal plane. The distance between this mirror and the focal plane is termed the focal length. A digital sensor or film can be kept on the focal plane for recording the image produced. At times, a secondary mirror is added to redirect/forward the focused light to a film, digital sensor, or an eyepiece for visually observing the optical characteristics.
In a majority of modern telescopes, the primary mirror is made of a solid glass cylinder with its front surface ground to a parabolic or spherical shape. A highly reflective front surface mirror is created by vacuum to deposit a thin layer of aluminum onto the mirror.
Different methods make primary telescopes. One such method involves rotating molten glass in order to make it is surface a paraboloid. This is continued till the glass cools down and solidifies. The mirror developed is paraboloidal in terms of shape approximately and requires minimal polishing and grinding for achieving the accurate figure.
Why are reflecting telescopes used for astronomical research?
At present, almost all large astronomical telescopes used for research are reflectors/reflecting telescopes. There are a variety of reasons why the reflectors are preferred for astronomical research:
· The glass elements/lenses used in refracting and catadioptric telescopes absorb specific wavelengths of light or a certain amount of incoming light. Reflectors do not absorb any such wavelength, and hence, they work on a broader spectrum of light.
· For a lens to work correctly, it should be devoid of any form of aberration, imperfection and inhomogeneities. The entire structure should be accurate. But in the case of mirrors. Only the reflecting surface requires to be perfectly polished.
· Lenses are made up of different materials with different refractive indices. Different wavelengths of light travel at different speeds and angles in different mediums. This results in giving rise to chromatic aberration. In order to correct these aberrations, one needs to incorporate a combination of two or more aperture-sized lenses. This increases the monetary investment of the system and also makes it significantly bulkier. The images formed by mirrors do not suffer from chromatic aberration. Moreover, mirrors prove out to be comparatively cost-efficient and are compact in size.
· Manufacturing and setting up lenses with large apertures can create problems. Lenses can be attached only with their edge. The central part of the lens slumps because of gravity. This leads to the distortion of the image formed. Using mirrors eradicates the possibilities of such problems. Mirrors can be held with back support and hence, can have large apertures without affecting image formation. The largest lens aperture currently stands at 1 m, whereas the largest mirror aperture stands at 10 m.
What are the different designs of reflecting telescope?
The Gregorian telescope (proposed by James Gregory) uses a concave secondary mirror to reflect the primary mirror’s image through a narrow hole. This is done to produce an upright image that is advantageous for conducting terrestrial observations. There are a few small spotting telescopes that are constructed in this manner. Many large modern telescopes also use the Gregorian arrangement. For example, the Magellan telescopes, the Vatican Advanced Technology Telescope, the Giant Magellan Telescope, and the Large Binocular Telescope.
The Newtonian telescope is a reflecting telescopic design variation that was developed by Sir Isaac Newton in the year 1668. Such telescopes incorporate a concave primary mirror and a flat diagonal secondary mirror. The Newtonian telescope is famous due to its effective and simplistic design, which is appreciated by telescope makers. In this design, the eyepiece is located at the top end of the telescope tube. The placement of the eyepiece with short focal ratios provides a compact mounting system, ensures mobility, and brings down the expenditure. [To know more about Newtonian telescope visit https://lambdageeks.com/newtonian-telescope/]
Path of light of a Newtonian Reflecting telescope. Image source: Krishnavedala – Own work CC BY-SA 4.0
The Cassegrain telescope that was developed by Laurent Cassegrain in the year 1672 incorporates a parabolic primary mirror and a hyperbolic secondary mirror for reflecting the incident light to the primary mirror through a small hole. The secondary mirror is primarily used for diverging and folding. This results in a telescope having a short tube length with a long focal length. [To learn more about Cassegrain telescope visit https://lambdageeks.com/cassegrain-telescope/]
Path of light of a Cassegrain Reflecting telescope. Image source; Krishnavedala – Own work CC BY-SA 4.0
The Ritchey–Chrétientelescope (developed by George Willis Ritchey and Henri Chrétien around 1910s) is a special Cassegrain reflector. This design has two hyperbolic mirrors instead of a parabolic primary mirror. The Ritchey–Chrétien telescope is free of coma and spherical aberration and provides a nearly flat focal plane. This telescope is apt for wide-field and photographic observations. The Ritchey–Chrétien telescope design happens to one of the most commonly used professional reflector telescopes.
The Dall–Kirkhamtelescope is another special type of Cassegrain telescope design. The Dall–Kirkham telescopic design is comparatively easier to construct than a regular Cassegrain or Ritchey–Chrétien telescope. However, this design is unable to correct the issues of off-axis coma. Its small field curvature makes it less evident or accurate at longer focal ratios; hence, Dall–Kirkham telescopes are barely seen to be faster than f/15.
The Herschelian reflector (proposed by William Herschel in 1789) is incorporated for building very large telescopes. The Herschelian design uses a tilted primary mirror. This ensures that the light is not blocked by head of the observer. However, this reflector design comes with certain geometrical aberrations. Irrespective of that, it is used for avoiding the use of a Newtonian secondary mirror. The secondary mirror is generally built up of speculum metal mirrors that gets tarnished fast and provides a reflectivity of only 60%.
Path of light of a Herschelian Reflecting telescope. Image source: User:Eudjinnius – Own work Diagram of Herschel-Lomonosov telescope system. CC BY-SA 3.0
What are the errors produced by reflecting telescope?
Reflecting telescopes are prone to producing specific errors while forming images, just like any other optical system. The images formed has object distances up to infinity, and these images are viewed at different light wavelengths. These factors cause specific errors in image formation.
Coma – Coma is a type of aberration that focuses the center of the image to a point, but the edges generally appear radially smudged (comet-like) or elongated.
Diagramatic representation of comatic aberration, anonymous, Lens-coma, CC BY-SA 3.0
Field curvature – At times, the images are not focused well all across the field. This happens due to the image plane’s curvature and is corrected by using a field flattening lens.
Astigmatism – Astigmatism is a type of aberration that causes an azimuthal focal variation around the aperture. As a result of this, off-axis point source images appear elliptical. Astigmatism causes more error when the field of view is large and starts varying quadratically with field angle. In the case of a smaller/narrower field of view, astigmatism is not usually a problem.
Distortion – Distortion is an aberration effect that disturbs the shape of the image. Image sharpness is not affected by distortion. This aberration is generally corrected with the help of image processing.
Spherical aberration: Spherical aberration is a defect that occurs when a spherical mirror/lens is unable to focus light from different distant objects at the same point. This defect is solved by using parabolic mirrors instead of the spherical ones. However, the parabolic mirror does not work well with image formation of light falling on the edge of its field of view and produces off-axis aberrations.
Newtonian telescopes are a type of reflecting telescope that use a primary mirror and a smaller secondary mirror to collect and focus light. They are known for their simplicity, affordability, and versatility, making them a popular choice among amateur astronomers. This comprehensive guide will delve into the technical details and specifications of Newtonian telescopes, providing a valuable resource for science students and enthusiasts alike.
Understanding the Aperture and Its Significance
The aperture of a Newtonian telescope is the diameter of the primary mirror, which is a crucial specification that determines the amount of light the telescope can collect. The aperture is directly proportional to the light-gathering power of the telescope, as described by the formula:
Light-gathering power = (Aperture diameter)^2
For example, the AWB 130 Newtonian Telescope has an aperture of 130mm, which is considered a medium-sized telescope. A larger aperture allows for more light to be collected, resulting in a brighter and clearer image, enabling the observation of fainter celestial objects.
Focal Length and Focal Ratio: Balancing Magnification and Field of View
Another important specification of a Newtonian telescope is the focal length, which is the distance between the primary mirror and the point where the light converges. The focal length determines the magnification and field of view of the telescope.
The focal ratio, denoted as f/x, is the ratio of the focal length to the aperture diameter. This ratio is a key factor in the telescope’s performance:
A telescope with a low focal ratio (e.g., f/4) has a wide field of view and is well-suited for observing large targets such as galaxies and nebulae.
A telescope with a high focal ratio (e.g., f/10) has a narrower field of view and is better for observing detailed features of planets and the moon.
The relationship between focal length and magnification is given by the formula:
Magnification = Focal length of the eyepiece / Focal length of the telescope
By carefully selecting the focal length and focal ratio, amateur astronomers can optimize their Newtonian telescopes for specific observational goals.
Mirroring Perfection: The Importance of Primary Mirror Quality
The quality of the primary mirror is crucial for the performance of a Newtonian telescope. The mirror should be figured (i.e., ground and polished) to a precise parabolic shape to minimize optical aberrations, such as coma and spherical aberration. The Standard Handbook for Telescope Making provides detailed instructions on how to figure and test a telescope mirror.
The surface quality of the mirror is also essential, as any imperfections or irregularities can degrade the image quality. The mirror’s reflectivity, determined by the coating material, also plays a role in the telescope’s light-gathering efficiency.
DIY Newtonian Telescope Building: A Hands-on Approach
For DIY enthusiasts, building a Newtonian telescope can be a rewarding and educational experience. Mel Bartels’ website, for example, provides detailed instructions on how to design and build a Newtonian telescope, including tips on choosing the right materials and tools.
When building a Newtonian telescope, key considerations include the mirror’s diameter, focal length, and the overall mechanical design to ensure stability and alignment. Proper mirror figuring and testing are also crucial steps in the construction process.
Newtonian Telescopes and Astrophotography: Balancing Focal Length and Field of View
Using a Newtonian telescope for astrophotography requires careful consideration of the trade-offs between focal length, field of view, and tracking accuracy. A longer focal length can provide higher magnification and resolution, but it may also result in a narrower field of view and increased sensitivity to tracking errors.
Conversely, a shorter focal length can provide a wider field of view and greater tolerance for tracking errors, but it may sacrifice resolution and magnification. The quality of the optics and the mount are also crucial for capturing sharp and detailed images.
Astrophotographers may need to experiment with different focal lengths and techniques to achieve their desired results, such as using focal reducers or Barlow lenses to adjust the effective focal length.
Conclusion
Newtonian telescopes are a versatile and popular choice among amateur astronomers, offering a balance of performance, affordability, and customization. By understanding the key specifications, such as aperture, focal length, and mirror quality, science students and enthusiasts can make informed decisions when selecting or building their own Newtonian telescopes.
Whether you’re interested in visual observation, astrophotography, or simply the joy of hands-on telescope building, this comprehensive guide provides the technical details and practical insights to help you explore the wonders of the night sky with a Newtonian telescope.
The list of articles on Tosca Tutorial are mentioned in the table of content which will be explain through out the entire Tutorial. All the the articles are written in simple languages with proper example which will help the entry level software tester to understand in short time.
In this article, we will start with TOSCA Overview. To get the flavors of Tosca interviews, you can check the most frequently asked interview questions with answers from here.
Tosca Overview
The purpose of this tutorial is to describe a complete and detailed overview of TOSCA as a test automation tool for beginners.
Concepts of Software Testing:
Software testing is an important step to assure the quality of software products. It ensures that the requirements are fullfilled as per the expectations. Testing can be done in the different phases of Software development life cycles. Those are –
Unit Testing – Done by software developer at the time of development.
Integration Testing – After developing the different components, each of the components need to be integrated to make an unique product. After the integration, the integration testing is required to verify that the entire setup (includes all the software components) is working fine as a single product.
System Testing – After the integration testing, the system testing is required to ensure the quality of the software.
User Acceptance Testing –
It is one type of black box testing. The business team (end user of the software product) is responsible to perform this testing to verify that all the requirements are fulfilled.
The Software or application testing can be performed manually or through some automated approach. There is multiple test automation tool is available in the marked to automate the testing process. In this article, we are going to explain the overview of TOSCA as a test automation tool.
What is Automation testing?
Today, the IT industry demands the quality and the efficacy with minimum human efforts to deliver any kind of IT services. Here, automation testing is playing a big role for testing services. Automation testing is a service to automate the testing process and scenarios to reduce the human efforts. In the automation vertical, the leading tools like QTP (UFT), RFT, and Selenium were consuming the major spaces. Now Tosca is giving tough competition to these tools.
Why Tosca?
Tosca is one of the market leading tool in the present days. It has the ability to perform functional and regression testing as well. The API testing which has n important role in AGILE process, can be done through TOSCA. Now a days, marked demands lesser testing efforts and lesser training span on the tool. In this aspect, Tosca is best suited tool as it supports the script less testing which will consume minimum time to learn. Tosca user can write efficient test cases with minimum skill set. Also, it generates a standard test reports for the management with out much customization.
Tosca Key Features:
Model-Based Testing Approach: This is the main features of Tosca as a test automation tool. Due to this Tosca is more suitable than other test automation tools which are available in the market. As a part of test case development, we have to create modules for each of the unit level functionalities. All the technical properties of test objects are stored in the modules which will be merged during the test creation along with test data.
Risk-Based Testing Approach: The another important aspect of Tosca as it supports the risk-based testing approach. Tosca is capable of assess the risk with the test cases. Basically, it can identify the subset of entire test suite which will minimize the chances of risks. Once the execution is completed, risks are measured by considering the test execution result and the risk coverage.
Script less test cases: Tosca supports script less automation which means that test cases can be developed by drag and drop method of modules in the TestCase section of Tosca. The test data parametrization and implementations of checkpoints, can be done through the configuration. So, anyone will be able to develop tests with minimum skillset and training.
Dynamic test data: The dynamic test data can be kept separately from the technical testcases. To achieve this, Tosca provides advance features such as, TDM, TCD, TDS etc.
Easy to maintain: If there is an application or data enhancement, same can be incorporated in the entire test suite by updating the modules or data in the central repository. The efforts spent here, is lesser with compare to any of the other test automation tools.
Distribute Execution: It signifies about the distribution of test execution in multiple system to reduce the human efforts and execution cycle. Based on the configuration of distributed execution, we can schedule the test execution in multiple systems.
API Testing: API testing is very useful when the entire application is not ready but some of the application components are developed. Using the API, Tosca is able to test the corresponding application components.
Test Recording: Tosca is able to record test scenario to generates linear test cases along with checkpoints to save time. This feature is very useful for one time testing only.
Detailed Reporting: Tosca generates step by step execution reports and logs with captured screens. The execution logs are very useful while investigating any errors.
Mobile Testing: Tosca supports the testing of mobile apps in both android and iOS devices. For iOS testing, additional MAC infrastructure is required.
Supported applications: Tosca is compatible with different types of applications such as Salesforce, SAP, Web, Powerbuilder, DotNet, Mainframe, Mobile devices, etc.
Integration with third-party tools: Tosca helps to integrate with third party tools with minimum customization such as Perfecto, Selenium, Azure, Jenkins etc.
TOSCA Architecture:
TOSCA is designed and developed by TRICENTIS Technology & Consulting GmbH (An Austrian Software Company based in Vienna). The test tool TOSCA have the below interfaces –
GUI – The Graphical User Interface
API – Application Programming Interface
CLI – Command Line Interface
Integrated Test Management
Architecture Diagram (Tosca Overview)
The latest version of TOSCA Commander which is available in the market is 13.3. The main components of Tosca are mentioned below –
Tosca Wizard
Tosca Commander
Tosca Executor
Test Repository
TOSCA Commander:
TOSCA commander is the core backbone of the tool to develop, manage, execute, and analysis of test scripts creation. Tosca Commander has the five sections which are used in most of the projects –
Module – All the Modules(keep the technical information of the test object) are stored in this section.
Testcase – The technical components of any test cases are kept in this section.
TestCaseDesign – This section is used to isolate the test data from the testcase in a well organized manner. The main intention of this section is not to touch the technical test cases to modify the test data.
Execution – This sections keeps the logs of test execution results in execution list. Basically, it is used to manage the test execution.
Requirements – All the requirements related information are stored in this section.
TOSCA Overview – Tosca Commander
A detailed study of different sections is available in the next article.
TOSCA Executor:
Tosca Executor is used to performing executing test cases that are developed in TOSCA. This is an alternative to test execution without opening the Tosca commander. We can navigate the Tosca executor through the windows start menu: Start-> All Programs-> Tricentis-> Tosca Executor.
To get more details on TestSet files, please click here.
Tosca Overview – Tosca Executor
Tosca wizard:
We need to scan the application to create modules (object map) for test automation. Tosca wizard is the old model of application scans. It can be open as a standalone component also from the Commander as well.
TOSCA Overview – Tosca Wizard
Test Repository:
Testcase can be stored in external shared repository/databases such as Oracle, SQLServer, SQL Lite, etc. Also, test data can be stored in an external repository in Tosca through different processes such as TDM – Test Data Management, TDS – Test Data Service. The test repository is required so that multiple testers can work at a time.
TOSCA Overview – Tosca Repository
Tosca Supported platform:
Frameworks and programming languages: dotNet including WPF, Java, VB, Delphi.
Web browsers: Firefox, Internet Explorer, Chrome.
Application Development Environment: PowerBuilder.
Host Applications: 3270, 5250.
MS programs: MS Outlook, MS excel
Enterprise Application: Seibel, SAP.
Protocols and hardware: Flash, Webservices (SOAP),ODBC.
Conclusion
In this introductory article of Tosca overview, we have covered the overview of Tricentis TOSCA testing tool, Tosca Commander and Workspace. Please click here, to navigate to the Tosca support portal for more information.
We going to start with Selenium tutorialBlackbook in exhaustive and different approach , In this first segment of the Selenium tutorial, we will discuss aboutSelenium Webdriver Architecture, what is Selenium Webdriver , Selenium Webdriver overview, Brief History of Selenium,Advantages of Selenium,limitations of Selenium, Selenium components and some frequently asked questions .
What is Selenium Webdriver
Selenium is an open source technology or framework through which we can automate Web based Applications. Selenium Supports Multi browser Testing, Multiple languages like Java, Ruby, Perl, Python is also supported. It supports different multiple platforms like Windows, Linux, macOS etc. as part of the platform.
Brief History About Selenium :
Selenium was initially evolved from an internal tool by Jason Huggins in 2004 at ThoughtWorks.
Later in the year of 2007, Huggins joined the organization Google, and with others like Jennifer Bevan, he continued with the design and development of one of the initial variations of Selenium called Selenium RC. During a similar time period, another person named as Simon Stewart from ThoughtWorks developed an advance web browser automation tools as WebDriver.
In 2008, a person named as Philippe Hanrigou from ThoughtWorks came up with remote Automation concepts known as “Selenium Grid”.
In 2009, at Google Test Automation Conference, it was decided to merge the two projects, and given the name as Selenium WebDriver, or Selenium 2.0.
Advantages of Selenium Webdriver :
A. Open Source :
Selenium is an open source technology/framework, hence huge community support is available where the development and improvement scope is rapid and vast, also as its open source you can implement any specific feature that you require as part of your work and contribute to the Open source community.
B. Multi Programming Language supported :
Selenium is supported by widely used languages; it comes up with different programming language bindings, so you can choose your favourable language to work with selenium as per your need and expertise.
Selenium provides support for the below programming languages :
Java
C#
Perl
python
Ruby
Javascript
C. Platform independent :
Selenium is platform-independent, so you can automate your web applications over any platform and any of the Operating System i.e. Windows, Linux, macOS etc.
D. Cross Browser Testing capability
Selenium supports cross browser Testing capability for your web applications; you can run your test suite written with Selenium in multiple browsers such as Firefox, Chrome, IE, Safari etc.
E. Cross Device Testing capability
Selenium Test Automation is used for mobile web application testing automation on various devices such as Android, IOS.
F. Remote or cloud execution :
Selenium GRID provides you with the feature to run and control your web application’s automation test script in the cloud by making one system as the master node and other system as the slave node, slave nodes connect to one master node, and master node monitors the slave nodes, so your tests are in different slave nodes with the different operating system and different browsers such as Chrome, Firefox, Internet Explorer etc.
G. Parallel Testing capability:
With Selenium, you can achieve Automated Parallel testing capabilities, i.e. you can run your test script or automation Test cases into the different or same browser and different or same operating system in parallel. This feature helps you achieve lesser execution time for the whole Automation Test suite that you have, and also you can test your web application’s feasibility and compatibility with multiple operating system and multiple browsers in parallel.
H. Compatibility with multiple Framework and third-party tools and technology
Selenium framework can be easily integrated with multiple various third party technologies and frameworks such as different Unit Test framework, i.e. TestNg, JUnit, MbUnit, Nunit etc. etc., different build Tools such as Ant, Maven, Gradle etc., continuous integration tools, i.e. Jenkins, different Test management tools such Jira, testlink etc., various reporting tools such as Allure, Extent Report etc.
I. Headless Browser execution :
Selenium Webdriver supports headless browser driver for automated test case execution, where all your automation test cases run in headless browser mode, i.e. no browser gets opened and the execution becomes lightning fast so you can complete you Test scripts and the functionality quickly in case of urgent release and validations.
You can basically use htmlUnitdriver or ghost driver for the headless execution with Selenium.
Disadvantages of Selenium :
Native/Window based App Support, not present :
Selenium is used for Automating Web Bade application, but it does not provide support for native applications or windows based applications.
Exhaustive Image-based Automation:
Selenium does not provide exhaustive support for automating image-based problems or applications, though we can use some third-party tools such as Sikuli, tesseract ocr based solutions which can be integrated with Selenium to do the job related to the Image validations/operations or image data extractions and validations, they are also having some limitations like you may face issues with Parallel testing, identifying handwritten document and validating those in the process of automating your application if there are such use cases.
Integration with third-party tools :
One downside of the integration with multiple third-party tools with selenium is that your automation script might become slower at times.
Designing and developing an advance Test Automation framework with Selenium requires a lot of expertise on selenium and its not too straight forward to build an Automation framework with multiple tools along with Selenium.
Browser Specific issues:
You may face some browser-specific issues while working with Selenium, especially with IE, sometimes you may not be able to handle Web actions like click, sendkeys etc., and the browser may become dead. Hence you need to have advance knowledge to handle those areas while automating Application built on Bootstrap JS and executing it on IE browser.
Also, you might face browser compatibility issues with the Selenium Webdriver versions; you need to make sure you are using the compatible Firefox, Chrome or any other browser you are working with Selenium Webdriver’s version.
No official support :
Like any other Open Source tools selenium is also an open-source tool, which means you will not have official support for your problems like any Paid Tools, even though there is very large community support available, you can work with them with you problem statement, but that can be heavily time-consuming.
Selenium Components :
Selenium as a tool has the below-mentioned components, which are :
Selenium IDE :
Selenium IDE or Selenium Integrated Development environment is the most initial version of Selenium for Web Application Automation.
Selenium IDE is a kind of record and playback tool, which you can use as a plugin of the browser and record you web action your you applications and that can be saved as a script and later you can run the same recorded script to execute and do validations.
But it has few limitations such as :
You need to run the recorded script, modifying the script is not that flexible or neither you can deign you use case and scripts in you own independent approach.
Execution is very slow in nature.
Majorly supports Firefox, though there are some tweaks you can do to run the recorded script in other browsers such as Google Chrome.
parallel execution is not supported.
Mobile testing is not supported.
Report generation is quite not good.
Its actually very preliminary version of Selenium, by using this you can do very limited Test Automation for your Web Applications.
Selenium RC
Selenium Remote Control is the next version of Selenium and very often its referred to as Selenium 1.0.
How Selenium RC works internally :
Selenium RC consists of two major components, such as Selenium Server, Selenium Client.
The Selenium Server launches the browsers and runs the selenium commands that you have written as a test automation script by using Selenium client libraries available in different languages.
Selenium Server converts the commands/test scripts into something called Selenese commands, and it acts as an HTTP proxy.
Selenium Server interacts with Web Browser engine and performs the Web operation that you are trying to Automate as part of Test cases for the Application Under the Test.
Steps to use Selenium RC :
Install the Selenium-RC Server.
Create a project using your choice of programming language and language specific to the browser driver.
Install selenium server
You can set up Selenium Server by simply just download the selenium-server.jar file and run it in your system by using the below command :
java -jar selenium-server.jar
Write the Script by using Selenium client libraries and the same using the Selenium Server.
Limitations of Selenium RC :
In Selenium Remote control, automation driver and browser becomes a bit slower reason being browser engine is not directly interacted, rather Selenium RC injects javascript to the browser engine, it also referred to as Selenium Core.
The Server which has to be up and running before and during the test script execution.
Advance Web actions can not be automated and handled using Selenium RC such as mouse Movement, double click, taking input from Keyboard etc. etc. unlike Selenium Webdriver.
Selenium RC does not support Mobile app testing.
Selenium RC is dependent on the real browser to run the Automation testing script, and it does not support the headless browser such as HTMLUnitDriver or GHostDriver etc. unlike Selenium Webdriver.
Selenium WebDriver:
Selenium Webdriver is the advance version among the Selenium components which is very robust and also supports the advance version of Web interactions and also it does not interact with Browser via Javascript unlike Selenium RC and has the Mobile Application testing support as well. It’s very often referred to as part of Selenium 2.0.
WebDriver can handle dynamic elements and also supports parallel execution with multiple different browsers.
We will have a detailed discussion in the upcoming segments.
Selenium GRID :
Selenium GRID is another component of Selenium through which you can have the remote execution of your automation testing script by creating master-slave nodes. Selenium GRID supports parallel Testing on the same browser as well as multiple browsers.
We will have further discussion on Selenium GRID in the upcoming sections.
WebDriver 3.0
Selenium 3.0 is the latest version of Selenium components which is basically the combination of WebDriver 2.0 and evolution of GRID 3.
In this next segment, we are about to discuss the Selenium WebDriver Architecture in detail, and eventually, it depicts how Selenium works internally,.
Selenium Webdriver Architecture :
There five major attributes or components as part of Selenium Webdriver architecture :
Selenium Client Library or Selenium-Programming language bindings
WebDriver protocol or JSON Wire Protocol over HTTP
Browser’s Drivers
Browsers Engine
Browser’s rendering Engine
Selenium Tutorial-Selenium Webdriver architecture
Selenium Client Libraries or Programming Language Bindings:
Selenium provides different language binding, i.e. the client libraries to support multiple different languages as part of your Automation Development and Automation test script. For example, Selenium with C#, Selenium with Java, Selenium with Python etc.
WebDriver Protocol or JSON WIRE PROTOCOL :
JSON which basically stands for JavaScript Object Notation. This protocol is also referred to as WebDriver protocol, used for server-client data transfer over the web. Each Browser Driver (e.g. FirefoxDriver, ChromeDriver etc.) has its own HTTP server and uses this protocol to transfer data via Rest Webservices in the form of the HTTP request and HTTP response.
Browser Drivers:
Each browser has its own browser driver. The Browser drivers establish communication with the respective browser via browser engine.
When the Automation script gets executed, it directly communicates to browser drivers and eventually with the respective browser. The request and response are transferred via HTTP request and HTTP response.
Browsers Engine :
Every Browser has its own browser engine; The browser engine basically works as an intermediary layer between UI and the rendering engine.
Browser Rendering engine :
The Browser rendering engine is responsible for displaying the requested document by rendering the specific elements required for the request-response and data.
Selenium Webdriver Architecture and working functionality in a nutshell :
Selenium-WebDriver invokes the browser directly using each browser’s native support for automation and its JavaScript engine. How these calls are being made and the features that they support depend on the browser you are using.
It does not inject JavaScript like Selenium-RC when the browser loads.
The following incidence occurs while running the Webdriver script:
We do the automation scripting using any language binding (Java / C # etc.), and it triggers the WebDriver API while the script is in execution.
The script and eventually commands (eg driver.findElement (By.id (“idName”))) are being converted to JavaScript internally.
Using Browser Engine, it is again converted back to JSON, which is kind of a key-value pair.
After getting the respective value of the respective key, it identifies the respective WebElements and performs the respective user actions (like click, send keys, etc.).
All communication is done using a JSON-Wire or Webdriver Protocol call, and the communications happen over HTTP in the form of Rest API as an HTTP request and HTTP response.
Selenium frequently asked Questions :
What are the types of WebDriver APIs available in Selenium?
Selenium Webdriver is an interface and has different language bindings for different programming languages such as Java, C#, python etc.,
Selenium Webdriver is majorly having two different variants such as :
Selenium Web driver local.
Selenium Web driver Remote.
The Selenium Web driver Local uses the API to work with the specific language binding, and you can work with these with you local execution, while on the other hand if you want to execute you automation testing scripts in Remote, then you need to use the remote Selenium Web driver APIs.
Explain What are the scenarios we cannot automate using Selenium?
Selenium does not provide a way to Automate the below areas of aspects of the application, which are :
For Selenium 2.0 minimum requirement is Java 1.7, on the other hand for Selenium 3.0, the minimum required Java version is 1.8
Selenium 3.0 requires GeckOdriver for Firefox version above 47, but this is not the case for Selenium 2.0
Selenium 3.0 supports modern browser such as Edge, Safari etc. but on the other hand for Selenium 2.0, browser driver for Mozilla, Chromedriver, IE which is developed by Selenium developers.
In Selenium 3, the support for mobile automation testing got removed, i.e. AndroidDriver and iPhoneDriver, and you have to use tools like Appium for mobile automation testing, which is not the case for Selenium 2.0.
Selenium 3.0 doesn’t support the Headless driver, i.e. HTMLUnitWebDriver, but Selenium 2.0 has the support for Headless execution, i.e. with HTMLUnitDriver or ghostdriver.
Within Selenium 3, the Selenium WebDriver has become W3C standard; on the other hand, Selenium Webdriver in Selenium 2.0 does not belong to W3C standard.
Conclusion : With this we complete the first segment of Selenium tutorial blackbook covering What is Selenium , Selenium Webdriver Architecture,Selenium overview, Pros and cons of Selenium, In the upcoming segment of Selenium tutorial module 2 we will be discussing about Selenium Installation ie setup , Selenium commands and other basic,intermediate and advance topics of Selenium
Using Appium Inspector, we will learn how to inspect element android and how to inspect element on the iPhone in this Appium tutorial. Appium provides the capability to inspect elements both in android and iOS.
How to inspect element on iPhone using Appium inspector
Step 1 →Opening iOS simulator
In this tutorial, for all the examples we have covered with the iOS simulator. To open the iOS simulator, follow the below process:
Step 2 →Getting “udid.”
To connect the Appium inspector with the Simulator, we need udid. To get the
booted udid, please run below command
xcrun simctl list | egrep ‘(Booted)’
it will list down the device id and name of the Simulator booted up recently
Step 3→ Getting OS version
Now we need the OS version of the Simulator. To get the OS version, please run the below command
instruments -s devices |grep “iPhone SE” [please replace the device name with the device name you got from above command]
Step 4→ Opening Appium Inspector
Now we have the device id and os version with us. Please click on the button highlighted in the below image. It will open the New Inspector.
Click on search
Step 5→ Connecting Appium inspector with Simulator
Now add all the desired capabilities required to start the session. Please follow the below image for the required desired capabilities and start the session.
If you want to verify with a specific app, you can add an app path. In this tutorial, W have worked with the existing “Contact” app in the Simulator.
Add desiredCapabilities
Start the session
Step 6→ Getting the default screen.
Once the session is started, you can see the Simulator’s home screen image and the XML hierarchy. Please look at the below image for more details.
Appium inspector
Step 7→Inspect and clicking on the contact.
Now click on the Simulator’s contact button to reflect the inspector’s screen and click on refresh. Alternatively, you can find the Xpath of the contact and click on Tap. Please see the image below.
How to inspect element on iPhone
Step 8→ How to start recording?
After clicking on Contacts, we will see the image below. Now click on “Start recording” to capture all the actions. It will help to generate the Appium scripts in the desired language.
Start recording
Step 9→Inspect the element and clicking on tap.
Please follow the highlighted portion in the below image. First, find the XPath of the “Add” button, and after that, click on the Tap button.
Perform actions from inspector
Step 10→Sending keys.
After tapping on the Add button below screen will appear. Please follow the highlighted part to send the value from the Appium Inspector itself.
Use sendKeys
Step 11→Typing hello.
Please write any value to update the “First Name” value and click on “Send keys.”
Type hello
Step 12→Value reflected in both the app.
The value will be reflected in both places, like in the image below. Appium inspector
as well as Simulator
value reflected in both app
Step 13→generating code.
Now click on the link shown below in the image. It will generate Automation scripts in the preferred language. Here language has been selected as Python. You can view this in the below image.
click to generate the code
Step 14→Sample code.
Below are the sample scripts generated by the Appium inspector. Here language has been selected as Java-Junit.
import io.appium.java_client.MobileElement;
import io.appium.java_client.ios.IOSDriver;
import junit.framework.TestCase;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.net.MalformedURLException;
import java.net.URL;
import org.openqa.selenium.
remote.DesiredCapabilities;
public class SampleTest {
private IOSDriver driver;
@Before
public void setUp() throws MalformedURLException {
DesiredCapabilities desiredCapabilities = new DesiredCapabilities();
desiredCapabilities
.setCapability("platformName", "iOS");
desiredCapabilities
.setCapability("platformVersion", "13.6");
desiredCapabilities
.setCapability("deviceName", "iPhone SE");
desiredCapabilities
.setCapability("automationName", "XCUITest");
desiredCapabilities
.setCapability("udid", "B5FDD9EB-05C6-4F3B-9DFE-1A4EC3E06A7F");
URL remoteUrl = new URL("http://localhost:4723/wd/hub");
driver = new IOSDriver(remoteUrl, desiredCapabilities);
}
@Test
public void sampleTest() {
MobileElement el1 = (MobileElement) driver
.findElementByAccessibilityId
("Contacts");
el1.click();
MobileElement el2 = (MobileElement) driver
.findElementByAccessibilityId("Add");
el2.click();
MobileElement el3 = (MobileElement) driver
.findElementByAccessibilityId("First name");
el3.sendKeys("Hello");
}
@After
public void tearDown() {
driver.quit();
}
}
Issues faced opening the Appium Inspector in Mac.
How will you solve issues like “Encountered internal error running the command: Error: Unknown device or simulator UDID?”
You need to install "libimobiledevice."
Please use command → brew install libimobiledevice --HEAD.
How will you solve it if you get “WebDriverAgent because of xcodebuild failure: not found: carthage” issue?
You need to install the carthage
Please use command→ brew install carthage.
How to inspect element on android using Appium inspector
Step 1 → Opening emulator
In this tutorial, for all the examples we have covered with the Android emulator. To open the Android emulator, follow the below mentioned process:
Step 2→ Opening the Appium inspector.
Now we have the device id and os version with us. Please click on the button highlighted in the below image. It will open the New Inspector.
Opening Appium inspector
Step 3→ Connecting Appium inspector with Simulator
Now add all the desired capabilities required to start the session. Please follow the below image for the required desired capabilities and start the session. If you want to verify with a specific app, you can add an app path. In this tutorial, we have worked with the existing “Contact” app in the emulator.
Adding desiredCapabilities
Step 4→ Opening home screen
Once the session is started, you can see the emulator’s home screen image and the XML hierarchy. Please refer to the below image for details.
Opening Home screen
Step 5→Inspect element and start recording.
Now click on the contact button from the emulator. Please see the below image for more details.
how to inspect element on android
Step 6→Clicking add button
After clicking on Contacts, we will see the image below(Here we have chosen the favorite tab and refresh the page from the inspector). Now click on “Start recording” to capture all the actions. It will help to generate the Appium scripts in the desired language. Please click on the tap button highlighted below.
Perform actions
Step 7→ Clicking on send keys.
After tapping on the Add button below screen will appear. Please follow the highlighted part to send the value from the Appium inspector itself.
click on sendKeys
Step 8→Typing Hello
Please write any value to update the “First Name” value and click on “Send keys.”
typing hello
Step 9→Generating code
The value will be reflected in the edit box, like in the image below. Appium inspector, as well as an emulator. To generate the code, click on the highlighted arrow.
Till now, we have discussed how to inspect element android and how to inspect element on iPhone. In the next topic, we will write about how to write the first script in Appium. To start the subject from the beginning, pleaseclick here. For more details for this section, please refer to this link.
The Bohr model of the hydrogen atom provides a fundamental understanding of the behavior of electrons in atoms, particularly the quantization of energy levels and the emission or absorption of specific wavelengths of light. This model, developed by Danish physicist Niels Bohr in 1913, laid the groundwork for our modern understanding of atomic structure and the quantum mechanical nature of electrons.
The Bohr Model: Key Principles
The Bohr model of the hydrogen atom is based on the following key principles:
Quantized Energy Levels: Electrons in a hydrogen atom can only occupy specific, discrete energy levels, rather than a continuous range of energies. These energy levels are characterized by the principal quantum number, n, which is an integer greater than 0.
Circular Orbits: Electrons in a hydrogen atom move in circular orbits around the nucleus, with each orbit corresponding to a specific energy level.
Stable Orbits: Electrons can only occupy stable orbits, where their angular momentum is quantized in units of Planck’s constant, h. This means that the electrons can only have certain allowed values of angular momentum.
Emission and Absorption: When an electron transitions from a higher energy level to a lower energy level, it emits a photon with a specific wavelength, determined by the energy difference between the two levels. Conversely, an electron can absorb a photon and transition to a higher energy level.
The Bohr Model Equation
The energy of a hydrogen atom in the nth energy level is given by the Bohr model equation:
E = -13.6 eV / n^2
where E is the energy of the atom in electron volts (eV), and n is the principal quantum number, an integer greater than 0.
Some key points about this equation:
The negative sign indicates that the electron is bound to the nucleus and has a lower energy than a free electron.
The energy levels are inversely proportional to the square of the principal quantum number, n.
The ground state (lowest energy level) of the hydrogen atom corresponds to n = 1, with an energy of -13.6 eV.
The first excited state corresponds to n = 2, with an energy of -3.4 eV.
The Rydberg Equation
The wavelength of light emitted or absorbed during a transition between energy levels in a hydrogen atom can be calculated using the Rydberg equation:
1/λ = R(1/n_f^2 - 1/n_i^2)
where:
– λ is the wavelength of the light
– R is the Rydberg constant, approximately 1.097 × 10^7 m^-1
– n_f is the final principal quantum number
– n_i is the initial principal quantum number
This equation allows us to predict the specific wavelengths of light that will be emitted or absorbed by a hydrogen atom during electron transitions between different energy levels.
Hydrogen Atom Transitions and Spectral Series
The transitions between energy levels in a hydrogen atom give rise to the characteristic line spectrum of hydrogen, which consists of several series of spectral lines:
Lyman Series: Transitions from higher energy levels (n > 1) to the ground state (n = 1). The Lyman series is in the ultraviolet region of the electromagnetic spectrum.
Balmer Series: Transitions from higher energy levels (n > 2) to the first excited state (n = 2). The Balmer series is in the visible region of the spectrum.
Paschen Series: Transitions from higher energy levels (n > 3) to the second excited state (n = 3). The Paschen series is in the near-infrared region.
Brackett Series: Transitions from higher energy levels (n > 4) to the third excited state (n = 4). The Brackett series is in the infrared region.
Pfund Series: Transitions from higher energy levels (n > 5) to the fourth excited state (n = 5). The Pfund series is also in the infrared region.
These spectral series provide valuable information about the energy levels and structure of the hydrogen atom, and they have been instrumental in the development of quantum mechanics and our understanding of atomic physics.
Limitations of the Bohr Model
While the Bohr model of the hydrogen atom provides a useful framework for understanding the behavior of electrons in atoms, it has several limitations:
Applicability: The Bohr model is only accurate for one-electron systems, such as the hydrogen atom. It fails to accurately describe the behavior of multi-electron atoms, where electron-electron interactions and other quantum mechanical effects become important.
Orbital Angular Momentum: The Bohr model does not fully account for the orbital angular momentum of electrons, which is a fundamental property in quantum mechanics.
Spin and Magnetic Moments: The Bohr model does not consider the spin of electrons or their associated magnetic moments, which are crucial in understanding the fine structure of atomic spectra.
Electron Probability Distributions: The Bohr model treats electrons as classical particles orbiting the nucleus, rather than as quantum mechanical wave functions with probability distributions.
Despite these limitations, the Bohr model remains an important stepping stone in the development of quantum mechanics and our understanding of atomic structure. It provides a valuable introduction to the concept of quantized energy levels and the emission and absorption of specific wavelengths of light by atoms.
Conclusion
The Bohr model of the hydrogen atom is a fundamental concept in atomic physics, providing a framework for understanding the behavior of electrons in atoms and the resulting line spectra. By introducing the idea of quantized energy levels and the emission and absorption of photons, the Bohr model laid the groundwork for the development of quantum mechanics and our modern understanding of atomic structure. While the model has its limitations, it remains an important tool for visualizing and explaining the basic principles of atomic physics.
References
“Bohr Model of an Atom | Overview, Importance & Diagrams” from Study.com
“Bohr’s Theory of the Hydrogen Atom” from Lumen Learning
“The Bohr Model of the Atom – Quantized Energy” from Ontario Tech University
Atomic Emission Spectroscopy (AES) is a powerful analytical technique that allows for the identification, quantification, and characterization of elements in a wide range of samples. This comprehensive guide delves into the various applications of AES, providing in-depth technical details and practical insights to help scientists and researchers leverage this versatile tool effectively.
Understanding the Principles of Atomic Emission Spectroscopy
Atomic Emission Spectroscopy is based on the principle that when atoms are excited to a higher energy state, they emit photons with specific wavelengths as they return to their ground state. The intensity of the emitted light is directly proportional to the concentration of the element in the sample, enabling both qualitative and quantitative analysis.
The excitation of atoms can be achieved through various methods, such as:
Flame Atomic Emission Spectroscopy (FAES): In this technique, the sample is introduced into a flame, where the heat energy excites the atoms.
Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES): This method uses a high-temperature plasma to atomize and excite the sample.
Spark Atomic Emission Spectroscopy (Spark AES): A spark is generated between an electrode and the sample, providing the energy to excite the atoms.
Each of these techniques has its own advantages and limitations, and the choice of method depends on the specific requirements of the analysis, such as the sample matrix, the elements of interest, and the desired detection limits.
Applications of Atomic Emission Spectroscopy
Atomic Emission Spectroscopy has a wide range of applications across various fields, including:
Environmental Analysis
AES is widely used in environmental analysis for the detection and quantification of heavy metals, trace elements, and other pollutants in water, soil, and air samples. For example, ICP-OES can measure the concentration of lead in water samples with a detection limit of 0.01 parts per billion (ppb), making it a valuable tool for monitoring water quality.
Metallurgy and Materials Science
AES techniques, such as Spark AES, are extensively used in the metal and materials industry for the analysis of alloy composition, quality control, and process monitoring. The technique can provide rapid, accurate, and simultaneous analysis of multiple elements in metal samples, with a typical linear range of 1 part per billion to 100%.
Geological and Mineral Analysis
AES is a crucial tool in the field of geology and mineralogy, where it is used to determine the elemental composition of rocks, ores, and minerals. ICP-OES, in particular, is widely employed for the analysis of major, minor, and trace elements in geological samples, with high precision and accuracy.
Food and Agricultural Analysis
AES techniques are used in the food and agricultural industries for the analysis of nutrient content, contaminants, and adulterants in food, beverages, and agricultural products. For instance, ICP-OES can be used to determine the concentration of essential minerals, such as calcium, iron, and zinc, in food samples.
Pharmaceutical and Biomedical Applications
AES is used in the pharmaceutical and biomedical fields for the analysis of active pharmaceutical ingredients, excipients, and biological samples. The technique can provide accurate quantification of trace elements, such as heavy metals, in drug formulations and biological matrices, ensuring product quality and safety.
Forensic Analysis
AES, particularly Spark AES, is employed in forensic investigations for the analysis of trace evidence, such as gunshot residue, paint chips, and metal fragments, helping to establish the identity and origin of the samples.
Semiconductor and Electronics Industry
AES is used in the semiconductor and electronics industry for the analysis of thin films, coatings, and electronic components, ensuring the purity and quality of materials used in the manufacturing process.
Advantages and Limitations of Atomic Emission Spectroscopy
Atomic Emission Spectroscopy offers several advantages, including:
High Sensitivity: AES techniques can detect elements at very low concentrations, with detection limits in the parts per billion (ppb) range for many elements.
Wide Linear Range: AES techniques typically have a wide linear range, allowing for the analysis of samples with a wide range of element concentrations.
Simultaneous Multielement Analysis: AES, particularly ICP-OES, enables the simultaneous determination of multiple elements in a single analysis, improving efficiency and throughput.
Minimal Sample Preparation: AES techniques often require minimal sample preparation, with liquid samples typically introduced directly into the instrument and solid samples requiring only simple digestion or ablation.
High Precision and Accuracy: AES techniques offer excellent precision, with relative standard deviations often below 1%, and accurate results, with recoveries close to 100% for many elements.
However, AES techniques also have some limitations, such as:
Spectral Interferences: AES can be affected by spectral interferences, where the emission lines of one element overlap with those of another, leading to inaccurate results. These interferences can be minimized through the use of high-resolution spectrometers and advanced data processing techniques.
Matrix Effects: The sample matrix can influence the excitation and emission characteristics of the analytes, leading to matrix effects that can affect the accuracy of the results. Careful sample preparation and the use of matrix-matched standards can help mitigate these effects.
Consumable Costs: The operation of AES instruments, particularly those using plasma sources, can be relatively expensive due to the high energy consumption and the need for specialized consumables, such as argon gas.
Complexity of Instrumentation: AES instruments, especially ICP-OES, can be complex and require skilled operators for proper operation and maintenance.
Practical Considerations and Best Practices
To ensure the effective and reliable use of Atomic Emission Spectroscopy, it is essential to consider the following practical aspects:
Sample Preparation: Proper sample preparation is crucial for accurate and reproducible results. This may involve digestion, dilution, or other pre-treatment steps to ensure the sample is in a suitable form for analysis.
Calibration and Standardization: Accurate calibration of the AES instrument using appropriate standards is essential to ensure the reliability of the results. The use of matrix-matched standards and internal standards can help compensate for matrix effects and improve the accuracy of the analysis.
Interference Correction: Spectral interferences can be mitigated through the use of high-resolution spectrometers, advanced data processing techniques, and the selection of appropriate analytical wavelengths.
Quality Control and Assurance: Implementing robust quality control and assurance measures, such as the analysis of reference materials, method validation, and regular instrument maintenance, is crucial to ensure the reliability and reproducibility of the results.
Data Analysis and Interpretation: Proper data analysis and interpretation are essential to extract meaningful information from the AES data. This may involve the use of statistical tools, data visualization techniques, and the consideration of relevant background information about the samples and the analytical method.
Conclusion
Atomic Emission Spectroscopy is a powerful analytical technique with a wide range of applications in various fields, from environmental analysis to materials science and biomedical research. By understanding the principles, capabilities, and limitations of AES, researchers and scientists can leverage this versatile tool to obtain accurate, reliable, and insightful data, contributing to advancements in their respective domains.
We will discuss how to use Appium methods in this Appium tutorial. Appium is a wrapper on top of Selenium webDriver. All the Selenium methods are already present in Appium. Apart from that, Appium provides a good number of ways to interact with native applications.
How to use the pressKey code using Appium methods?
public void pressKeyCode(AndroidKey code) {
\tandroidDriver.pressKey(new KeyEvent(code));
\t }
Here you can pass keyEvent like AndroidKey.ENTER to enter or AndroidKey.BACK to tap
on
back button Similarly, users can use this for long key presses like:
public void longPressKeyCode(AndroidKey code) {
\tandroidDriver.longPressKey(new KeyEvent(code));
\t}
How to get the current activity using Appium commands?
To get the current activity, we can use the current Activity method.
For Example:
public String currentActivity() {
\treturn androidDriver.currentActivity();
\t }
How to check if the app is installed or not?
To check if the app is installed or not we can use:
public boolean isAppInstalled(String bundleId) {
return androidDriver
.isAppInstalled(bundleId);
}
How to start activity in Android using Appium methods?
Please follow the below method to start the activity:
public void startActivity(String packageName, String activity) {
try {
androidDriver.startActivity(new Activity(packageName, activity));
} catch (Exception e) {
\t e.printStackTrace();
}
How to scroll to a particular text using Appium methods?
public MobileElement scrollTo(String text) {
MobileElement textFinder = androidDriver
.findElementByAndroidUIAutomator
("new UiScrollable(new UiSelector()"
+ ".resourceId(\\"android:id/list\\"))
.scrollIntoView("
+ "new UiSelector().text(\\"" + text + "\\"));");
\t return textFinder;
}
How to hide the keyboard using Appium methods?
public void hideKeyboard() {
try {
androidDriver.hideKeyboard();
} catch (Exception e) {
LoggerUtils.error("Exception in hiding keyboard" + e.getMessage());
}
How to get progress dialog using Appium methods?
public MobileElement getProgressDialog() {
return androidDriver
.findElementById
("android:id/progress");
}
Till now, We have discussed about the top 20 most used Appium methods. In the next topic, We will write about the Appium Inspector for Android and iOS. For more details for this section, please refer to this link.
