Question

When a drop of oil is spread on water surface, it displays beautiful colors in daylight because of
(A) Dispersion of light
(B) Reflection of light
(c ) Polarization of light
(D) Interference of light

Answer 1

Hint: When a drop of oil is spread on the water surface, beautiful colors appear in daylight because of the oil film, when light is incident on the upper and lower surface and some of the light is reflected. This process takes place when the two incident lights are of same wavelengths. Thus using this concept you can find the phenomenon employed here.

Complete answer:
The bright colors seen in an oil film or in the soap bubble are caused by interference. The brightest colors are those that interfere constructively. This interference is between light reflected from upper and lower surfaces of the film; thus, the effect is understood as thin film interference. As noticed before, interference effects are most prominent when light interacts with something having a size almost like its wavelength.
When a drop of oil is spread on a water surface, it displays beautiful colors that appear in daylight because of interference of light. Here some of the light is reflected off the top surface and some the bottom surface. Because the thickness of the oil film is about an equivalent because the wavelength of the sunshine the 2 reflected rays interfere with one another.
Here interference of light is taking place.

So, the correct answer is “Option D”.

Note:
Interference is the process by which the two incident lights combine together to form a new wave of combination. This process is called interference of light. Since the incident light here is daylight, which is white in coloured forms different colours are interfering. This is because white light contains all wavelengths of visible spectrum.