Question

When a compact disc is illuminated by a source of white light, coloured lines are observed. This is due to:
(A) Dispersion
(B) Diffraction
(C) Interference
(D) Refraction

Answer 1

Hint : Follow the properties of the scattering of light waves and its properties. It depends on the wavelength and the medium through which it travels. Here we will go through all the terminologies with example and then will identify the correct option.

Complete Step By Step Answer:
The phenomenon of splitting one light into the components of colourful lights is known as the dispersion of the light. For Example: Rainbow during the rainy-season and when light is passed through prism it splits into rainbow like structure.
The slight bending of the light when it passes around the edge of an object is due to the diffraction. For example – Light Entering and bending around the corners of the doors and windows.
A compact disc contains many fine circular lines on it and so it acts as the diffraction grating. When white light falls upon it and it is diffracted and different colours as a result of which the light is diffracted at different angles. We could see different colours when we look at the different angles.
The option B is the correct answer.

Note :
Know the difference between the reflection and refraction of light. The reflection of light is the change in the direction of the wave-front between the two different medium whereas refraction of light is the bending of light when it passes from one transparent substance into another.