Question

To observe diffraction the size of an obstacle
(a) Should be of the same order as wavelength
(b) Should be much larger than the wavelength
(c) Have no relation to wavelength
(d) Should be exactly $\frac{\lambda}{2}$

Answer 1

(a) Should be of the same order as wavelength

Answer 2

Answer: (a) Should be of the same order as wavelength.

Explanation:

Diffraction is basically bending of waves.

The bending occurs due to obstacles.

It occurs only when the the wavelength is comaparable 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 obstacle is directly proportional to the wavelength of source.

Suppose a is diffraction and λ is the wavelength a ∝ λ

Hence for diffraction, size of obstacle should be in order of wavelength