Two beam of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is `(pi)/(2)` at point A and `pi` at point B. Then the difference between resultant intensities at A and B is : `(2001 , 2M)`

Options

A. 2 I
B. 4 I
C. 5 I
D. 7 I

Answer

B

Explanation

`I_(A)=I+4I+2sqrt(Ixx4I)cospi//2=5I`
and `I_(B)=I+4I+2sqrt(Ixx4I)cospi=I`
So `I_(A)-I_(B)=5I-I=4I`