Direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by (a is the width of the slit)

Explanation

The condition for the secondary maxima is given by `phi=(m+(1)/(2))pi`, for m = 1,2,3
Substituting this value in equation, we get `(I)/(I_(0))=((sinphi)/(phi))^(2)=[(sin(m+(1)/(2))pi)/((m+(1)/(2))pi)]` For m=1 `1=(I_(0))/(121)`