In this article, we will discuss different properties of refraction, the wave characteristics, properties of light with exhaustive details and facts.
Here is a list of properties of reflection as follows that we are going to ponder upon in this topic:-
Wave Properties of Reflection
A wave function is used to describe the wave and a point behavior of a particle explicitly, which tells us about the position of the particle traveling in a wave at a certain instant, the number of waves, its angular frequency, and the amplitude of the wave.
If the wave function of a wave incident on the plane surface is given as
Ψ =A\ Sin (kx-ω t)
Where Ψ is a denotation of wave function
A is an amplitude
k is a wave number
x is a position of a particle
ω is an angular frequency
t is a time
Then, after reflection, the wave function becomes
Ψ =A\ Sin (kx-ω t + π)
Since, Sinπ =0 & Cosπ =-1
Therefore, we get
Ψ =-A\ Sin (kx+Ψ t)
Let us discuss below, the different properties of light traveling as a wave in the medium.
1. The Amplitude of the Wave after Reflection Remains the Same
The incident wave, after reflection at a certain angle in a medium having the same refractive index, propagates with the same amplitude.
The orientation of the amplitude of a wave might be in the negative y-axis after reflection if the direction of the propagation of the wave is denoted as positive x-axis, that is the amplitude can be negative, but the length of the amplitude remains the same.
2. The Frequency of the Wave is Constant
The energy of the wave before and after reflection is conserved, and hence the frequency of the wave is also conserved.
The frequency of the wave is always sustained even if the wave propagates into a medium having a different refractive index. As the speed of the wave changes, the wavelength varies with respect to the speed, as the speed is directly proportional to the wavelength; hence, the frequency of the wave is constant.
3. Speed and Wavelength is Sustained
If the wave propagates in the same medium then the amplitude and hence the wavelength remains unchanged.
In that case, the wave must be propagating in the medium having a unique refractive index, otherwise, the wavelength will reduce or enlarge depending upon the density of the medium and the amplitude will vary accordingly, increasing or decreasing the speed of wave respectively.
4. Path Propagation is in Opposite Direction
After reflection, the wave travels in the opposite direction away from the surface on which the wave was incident upon.
Though, the incident and the reflected waves lie in the same plane, the direction of propagation of the wave changes after reflection.
Properties of Reflection of Light
The light rays incident on the plane surface travels back to the same medium from which the light is been incident then we call it the reflection of light. Let us now discuss some properties of reflection of light below.
1. The Incident Ray, Reflected Ray, and Normal lie in an Identical Plane
A line arousing from a point where the incident ray meets the plane surface makes a normal of the surface. The light on reflection propagates back to the same medium by changing the direction of propagation. Hence, the ray of the incident, the normal and the reflected ray, all lie in the same plane.
2. Light Reflects only from Smooth Surfaces
The light rays are reflected from the plane, smooth surfaces only and not from the rough surface.
The light gets scatters if incident on the rough surfaces. This is called diffuse reflection, where the light rays after reflection travel in different paths and get scattered, and only the object from which the light is scattered is observable and not the images of the object from which the light has passed.
The light rays after reflection if travels in a single direction then it is known as a specular reflection. This is seen only when the light is incident on the smooth surfaces and light does not get scattered.
3. Angle of Reflection is Twinning to Angle of Incident
The normal plane lies perpendicular to the surface and intersects the point where the light ray is incident on the surface. The light after reflection travels making a reflective angle with the normal.
The incident ray of light makes an angle with the normal, which is equal to the angle of reflection formed by the reflected ray of light. The above figure depicts the same.
4. Incident Angle and Reflected Angle are Adjacent to each other with Normal
Both, the incident angle and reflected angle lies adjacent to the normal and opposite to each other.
The incident and the reflected ray meet the normal to form and incident angle and the reflected angle respectively, at a point where the light ray is incident upon the surface in the same plane.
5. The Reflected Rays form Symmetric Images
The reflected ray from the light incident upon the reflecting surface forms the mirror images which are symmetric to each other.
The normal to the plane forms the symmetric axis, which differentiates the real and the reflected image by a plane.
6. A Virtual Image is formed due to Reflection
Virtual images are the images of the objects formed behind the mirror, that are imagined to be present at that position but in actuality, these images do not exist.
Consider yourself standing infront of a large plane mirror. Your reflection is formed on the mirror. A person standing at a distance when observing you from the mirror will receive not your actual image but the virtual image that appears to form behind the mirror.
The image formed on the plane mirror is a virtual image of the object which is reflected and received by the observer’s eyes. Hence, all the mirrors are said to produce virtual images of the objects as they form symmetric and reflected images.
7. The Angle of Incident Determines the Intensity of Light Reflected from the Surface
The intensity of the reflected ray is minimum when the angle of the incident is small because more of the light rays traverse through the medium.
As the angle of incident increases, more of the light rays are reflected back and there is less of the transmission of the light therefore the intensity of the reflected ray is more at a greater incident angle.
Frequently Asked Questions
Q1. If the light is incident on the plane mirror making an angle of 35 degrees with the surface of the mirror, then, calculate the angle of reflection.
The normal makes an angle 90 degrees with the surface of a mirror. The angle between the incident ray and the surface of the mirror is 35 degrees, then the angle of the incident is equal to
Since, θi=θr as per law of reflection.
Hence the angle of reflection is equal
Does the intensity of the light change on reflection?
The part of the light incident on the surface is refracted; hence only the part of the waves of light is reflected back thus reducing the intensity of the light.