Question
Mon May 30, 2011 By: Saravanan Kannan

find the ratio of intensities of two points P and Q on a screen in a YDSE when the waves from sources S1 and S2 have phase difference 0 and pi/2.

Expert Reply
Thu June 02, 2011
Let I0 be the intensity of either of the interfering sources, the intensity I at a point P is  where d is the phase difference at p between the two disturbances.
d = 00 ; I = 4Io cos2(00)
............(i)
Let I0 be the intensity of either of the interfering sources, the intensity I at a point Q is  where d is the phase difference at p between the two disturbances.
d = 900 ; I = 4Io cos2(450)

..........(ii)

Dividing (i) by (ii), we get the ratio as 2:1

Ask the Expert