A slit of variable width illuminated by light of wavelength λ is widened until the first order diffraction minimum moves out to a distance infinitely far away from the brightest location in the central maximum. In terms of the wavelength, the width of the slit is then
A)0.
B) .
C)λ.
D) .
E)2λ.

Question

A slit of variable width illuminated by light of wavelength λ is widened until the first order diffraction minimum moves out to a distance infinitely far away from the brightest location in the central maximum. In terms of the wavelength, the width of the slit is then
A)0. 
B) . 
C)λ. 
D) . 
E)2λ.

Quizplus · Accepted Answer

The condition for the first order diffraction minimum to move to infinity is when the angle of diffraction, θ, satisfies sinθ = ±1. This occurs when the width of the slit, a, is equal to λ. Therefore, the width of the slit is λ.

A Slit of Variable Width Illuminated by Light of Wavelength