Question

Why is it much more difficult to see interference fringes for light reflected from a thick piece of glass than from a thin film? Would it be easier if monochromatic light were used?

Short answer

The thickness of the film should be comparable to the wavelength of light for an interference pattern. Monochromatic light does produce an excellent interference pattern.

Step-by-step solution

Definition of monochromatic light

Monochromatic light is light with a single wavelength.

Determining why it is difficult to observe interference fringe for light

Interference occurs when two waves of light superimpose to produce a consequent wave with a different amplitude. When the thickness of the interface surface is comparable to the wavelength of light, the interference pattern is visible.

As a result, interference fringes appear more clearly on the thin film than on the thick piece of glass. Using a monochromatic light beam, interference fringes can be easily noticed.

Therefore, on the thin film, the interference pattern is visible.