Question

Consider the following statements about interference of light. 
A – When crest of one wave coincides with crest of another wave at a point, this point is a point of destructive interference. 
B – Two coherent sources emit wave of same frequency with constant phase difference.
Choose the correct option from the following.

• A. Both statements A and B are wrong.
• B. Statement B is correct while statement A is wrong
• C. Statement A is correct while statement B is wrong.
• D. Both statements A and B are correct.

Answer 1

The Correct Option is B

Statement A: When the crest of one wave coincides with the crest of another wave at a point, this point is a point of destructive interference. 
This statement is incorrect. When the crests of two waves coincide, it is a point of constructive interference, not destructive interference. Constructive interference occurs when the amplitudes of the waves add up, resulting in a wave with a larger amplitude. 
Statement B: Two coherent sources emit waves of the same frequency with a constant phase difference. 
This statement is correct. Coherent sources emit waves with a constant phase difference, which means that the peaks and troughs of the waves maintain a fixed relationship as they propagate. 
Therefore, the correct option is (B) Statement B is correct while statement A is wrong.