There are different ways of heat transfer like conduction, convection and radiation. In this article we will see how is heat transferred by radiation in detail.
As opposed to conduction and convection, radiation is a mode of heat transfer that does not need any physical contact between the source of heat and the heated item, as is the case with both. Thermal radiation, often known as infrared radiation, has the capability of transmitting heat through empty space. This is a type of an electromagnetic radiation that is used in electronics. When radiation occurs, no mass is transferred, and no medium is required to facilitate the process. There are many radiation heat transfer examples in our day to day life like the sunlight, campfire, coal etc.
Thermal radiation is produced by the internal collision of particles in a matter when its temperature rises beyond the absolute zero degree Celsius. Thermal radiation is always emitted by all matter with a temperature greater than the absolute zero degree Celsius. In the same way that all other electromagnetic radiations do, thermal radiation may travel across space without the need for a medium, and that is why energy from the Sun can reach the Earth.
Radiation created by inter-atomic collisions among charged particles, which transfer energy away from the emitting body in the form of electromagnetic radiation, is referred to as thermal radiation or infrared radiation. These rays of energy can be absorbed by other distant objects, which results in an increase in the internal energy of the particles of that item. This causes the particles in that item to travel faster and collide more frequently, releasing energy in the form of heat and resulting into the rise in the temperature of the object in question.
Thermal radiation, as opposed to other types of heat transmission such as conduction or convection, may be focussed on a focal point by employing reflecting mirrors, which is what is done in solar energy generation to generate electricity.
The Stefan-Boltzmann Constant could be used to calculate the rate at which heat energy is transferred by radiation.
Where, 𝑸 = heat flux
𝝈 = Stefan-Boltzman constant
T = Absolute temperature
The heat transfer in two bodies can be calculated as follows :
The scientific explanation for radiation heat transfer states that all stuff above absolute zero generates electromagnetic radiation due to charged particle oscillations. Thus, everything in our cosmos emits radiation.
Q. What do you mean by heat?
Ans: In simple words heat is just a feeling of warmth.
Molecules and atoms are the building blocks of all material. These atoms are constantly moving in a variety of directions (translation, rotational, vibrational). The movement of atoms and molecules results in the generation of heat or thermal energy. Thermal energy may be found in all stuff. The greater the amount of motion that the atoms or molecules have, the greater the amount of heat or thermal energy that they will have.
Q. What do you mean by temperature?
Ans: A quantity that represents the sensations of hotness and coolness.
The average value of energy for all of the atoms and molecules in a specified system is represented by the temperature. The temperature of a system is independent of the amount of substance present in the system. It is nothing more than a means of the energy of a system as a whole.
Q. How does heat get transferred?
Ans: Heat may be transferred from one location to another by three different mechanisms: conduction, convection, and radiation.
Both conduction and convection need the transfer of heat to be accomplished through the use of materials. The transmission of heat energy from one system to another is unavoidable if there is indeed a temperature differential between the two.
- Conduction: The movement of heat energy between materials that are in direct touch with one another is referred to as conduction. Better is the conductivity of the material, the faster heat will be transported. Metal has excellent heat conduction properties. When the heat is provided to a material, the particles gain more energy and vibrate more, which is referred to as conduction. These molecules then collide with neighbouring particles, transferring some of its energy to them in the process. This process then continues, transferring energy from the heated end of the material to the cooler end of the material.
- Convection: Convection is the process through which thermal energy is transported from hot to cold environments. When warmer portions of a liquid or gas rise to the surface of a colder area of the liquid or gas, convection occurs. After then, a cooler liquid or gas takes the place of the warmer regions that have climbed higher in the atmosphere. As a result, a continuous circulation pattern is created. The convection currents created by boiling water in a pan are an excellent example. Convection may also be seen in the atmosphere, which is another notable example. When the earth’s surface gets heated by the sun, warm air rises and cold air moves in, creating a greenhouse effect.
- Radiation: As opposed to conduction and convection, radiation is a form of heat transfer which does not need any body interaction between the source of heat and the heated item, as is the case with both. Thermal radiation, often known as infrared radiation, has the capability of transmitting heat through empty space. This is a type of electromagnetic radiation that is used in electronics. When radiation occurs, no mass is transferred, and no medium is needed to facilitate the process. Radiation can be represented by the heat emitted by the sun or the heat emitted by the filament of a light bulb, for example.
Q. Which of the processes is considered to be a rapid process in heat transfer?
Ans: Radiation heat transfer is the fast and rapid process as compared to the other two types of heat transfer namely conduction and convection.
We all know that radiation is the most efficient route of heat transmission since radiation travels at the speed of light, which is extremely fast. Conduction is the slowest form of heat transport since it occurs from particle to particle and is thus the most inefficient.