Three narrow slits A, B and C are illuminated by a parallel beam of light of wavelength` lambda` , P is a point on the screen exactly in front of point A. Slit plane is at a distance D from the screen`(D gtgt lambda)`. It is know that `"BP – AP ="(1)/(3)`

(a) Find d in terms of D and` lambda`
(b) Write the phase difference between waves reaching at P from C and A.
(c) If intensity of P due to any of the three slits individu- ally is `I_(0)`, find the resultant intensity at P.

Answer

`(a)sqrt((2Dlambda)/(3))` `(b)(8pi)/(3)` `(c)3I_(0)`