Q.44. If diffraction occurs through a single slit then intensity of first secondary maxima become ............... of central maxima :-
(1) 4%
(2) 25%
(3) 75%
(d) 50%

Dear Student ,
At the centre all the Huygen sources from the slit opening interfere constructively and give you the maxima. 

But as you move away from the centre, and move towards the first order maxima, some Huygen sources kill each other, and the remaining construct to give light. So it would be less bright .
Mathematically the intensity of second ary Maxima is given by I = Im {sinA/A}2 where Im is the intensity of central maxima .For maxima A= (n+1/2)π. The relative intensity of first secondary maxima occurs at n=1.Therefore I1=Im(sin1.5π/1.5π) this is equal to .004 Im or I1/Im=4.5%.


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