Question

The bending of light near the edges of an obstacle and spreading into the region of geometrical shadow is called ……………
(A) Interference
(B) Diffraction
(C) Polarization
(D) Doppler effect

Answer 1

Hint: Interference has to do with superposition of waves. Polarization has to do with making random vibrations to become orderly in one plane. Doppler effect has to do with perception of sound by an observer.

Complete Step-by-Step Solution:
To answer this question, we need to compare the given statement to the definitions of each of the given options, to identify the match.
For option A, we have interference.
Interference is the superposition of two coherent light sources. The resulting light is a sum of the two waves depending on how they are superposed. If the crest of the first wave coincides with the crest of the other, the amplitude of the resulting wave is the sum of the amplitude of the two waves. However, if the crest of one combines with the trough of the other, then the resulting wave is a subtraction of the amplitudes.
For option B we have diffraction.
Diffraction is, in simple terms, the bending of light waves around an obstacle. This changes the immediate direction of some part of the wave by spreading throughout the region. Diffraction may cause interference, if the diffracted waves from the same source are allowed to recombine with each other, like in the cases of Young’s Slit experiments.

Hence, the correct answer is B

Note: For clarity, two waves are said to be coherent if their waveform and frequency is perfectly identical, and they both have a constant phase difference. This is why diffraction may cause interference. If a light wave is split into two due to diffraction, since they come from the same source (it was one light wave), they are coherent. Hence when they recombine, they superimpose to create interference.