Question

Match the following columns and choose the correct options from the codes given below.

Column I		Column II
A	Constructive interference	1	$n\lambda$
B	Destructive interference	2	$(n+1)\lambda /2$
C	Path difference for constructive interference	3	Waves are in phase at point of interference
D	Path difference for destructive interference	4	Waves are out of phase at point of interference

• A. $A\to 4,B\to 1,C\to 3,D\to 2$
• B. $A\to 4,B\to 3,C\to 1,D\to 2$
• C. $A\to 3,B\to 4,C\to 1,D\to 2$
• D. $A\to 3,B\to 4,C\to 2,D\to 1$

Answer 1

Answer: (C)

A constructive interference is produced when waves overlaps such that a crest meets a crest and waves are in phase.

For maxima,
$S_{1}P\sim S_{2}P=n\lambda (n=0,1,2,3,\dots )$
For minima,
$S_{1}P\sim S_{2}P=\left(n+\frac{1}{2}\right)\lambda (n=0,1,2,3,\cdots )$
we will have destructive interference and the resultant intensity will be zero.