NEET2018PhysicsWave OpticsActual
Assertion : Colours are seen in thin layers of oil on the surface of water. Reason : White light is composed of several colours.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIf both assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
Step-by-step solution
Colours are seen in thin layer of oil on the surface of water, because of interference of light. When white light falls on a thin film of a liquid it will appear bright having colour whose wavelength satisfies the relation 2 t r=(2 n+1) / 2 . The colour of the film will depend upon the thickness of the film and the angle of refraction.