Question

When exposed to sunlight, thin films of oil on water often exhibit brilliant colors due to the phenomenon of

• A. Interference
• B. Diffraction
• C. Dispersion
• D. Polarisation

Answer 1

The correct option is A

Interference

Explanation for the correct option:

Option A:

1. Interference due to thin films is a natural phenomenon occurring due to the reflection of light waves between the two surfaces whose distances are comparable with the wavelength.
2. In this thin film of oil which is spread over a surface acts as a thin film and the light waves reflect from the top and bottom surfaces of a film of oil and these two waves interfere with one another.
3. In the case of sunlight also the light waves reflect and form an interference pattern.
4. When the retardation between the waves of the crystal is equal to a whole number of wavelengths corresponding to its complementary colour then the interference colour is produced.

Explanation for the wrong answer:

Option B:

1. Diffraction is a phenomenon of bending of light around the sharp edges are obstacles whose wavelength is comparable with the width of the slit.

Option C:

1. Dispersion is splitting up of white light into its constituent colours on passing through a prism.

Option D:

1. Polarisation is the restriction of the vibration in a transverse waves.

Hence, Option A is the correct answer.