Question

During a straight-edge diffraction experiment, a light of wavelength 400 nm was used. What would be the position of the first minimum, if the separation between the edge and the source is 10 cm while that between the edge and eyepiece is 2 m?

(a) 1.01 cm

(b) 2.03 cm

(c) 0.57 cm

(d) 1.56 cm

Answer 1

Correct option is (c) 0.57 cm

Explanation: λ = 4000 Å = 4 X 10^-5cm, a = 10 cm and b = 200 cm

Location for first maximum, x1 = (sqrt{frac{2b(a+b)lambda}{a}})

= (sqrt{0.336})cm

= 0.57 cm.