Question

To observe diffraction, the size of an obstacle:

• A. should be of the same order as wave length
• B. should be much larger than the wave length
• C. has no relation to wave length
• D. may be greater or smaller than the wave length

Answer 1

The correct option is A should be of the same order as wave length

Diffraction is basically the bending of waves. The bending occurs due to obstacles. It occurs only when the wavelength is comparable to the size of aperture. As the wavelength increases, the diffraction effect will also increase.

Thus for greater diffraction, it is important that the size of the obstacle is directly proportional to the wavelength of the source. Suppose a is diffraction and $\lambda$ is the wavelength $a\propto \lambda$ Hence for diffraction, size of obstacle should be in the order of a wavelength