Question

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

Options

• a sin θ = `lambda/2`

• a cos θ = `(3 lambda)/2`

• a sin θ = `lambda`

• a sin θ = `(3 lambda)/2`

Answer 1

a sin θ = `(3 lambda)/2`

Explanation:

Relation for the maximum

`((2"n" + 1)lambda)/2` = a sin θ

`((2 xx 1 + 1)lambda)/2 = "a" sin theta` [n = 1]

`(3lambda)/2` = a sin θ