The correct option is C D=15λ4
The maximum and minimum path difference between the waves are, 2λ
(when point P
is very close to S2
) and zero (when point P
is at infinity), respectively.
For any minima, the path difference is equal to odd multiple of λ2
Only two minima obtained from S2
till infinity, along the line S2P
Close to S2
, the path difference is 2λ
. As we move away from S2
, along the line S2P
, the path difference starts to decrease.
The farthest minima will have a path difference λ/2
and the nearest minima will have a path difference of 3λ2
Now, for the farthest minima,
is the correct answer.