Question

When light is refracted from a surface, which of its following physical parameters does not change?
A. Velocity
B. Amplitude
C. Frequency
D. Wavelength

Answer 1

Hint: As a first step, one could read the question along with the options given. Then one could recall the concept of refraction and also the related important points. Then one could approach the given options one by one. Hence, find the quantity that remains unchanged on the light being refracted.

Complete step-by-step solution: -
In the question, we are given the case of a light that is refracted from a surface and we are asked to find the physical parameters that don't change after being refracted from that surface from the given options.
Let us consider each of the given options one by one.
Firstly, we have the velocity of the light. We know that velocity of light is dependant on the medium and is given by,
$v=\dfrac{c}{n}$
So, velocity will change.
Now for amplitude;
Though for complete refraction of light from a surface the amplitude would remain the same but normally refraction is accompanied by the reflection and this would result in change in amplitude in the process.
Now for the case of wavelength;
The wavelength of light is known to have an inverse relation with refractive index and hence is dependent on the medium.
For the case of frequency which is solely determined by the source and is also independent of the medium, it doesn't change on being refracted from a surface.
Hence, option C frequency is the quantity that doesn’t change on light being refracted from a surface.

Note: Refraction can be defined as the process in which the direction of a wave changes on passing from one medium to another. Not only light but other waves like the sound waves and even the water waves do experience refraction. Optical instruments like the lenses, magnifying glass, prisms are based on this phenomenon.