Light is shone through an adjustable-width slit in an otherwise opaque barrier, and a diffraction pattern is observed. If the slit is decreased to half its original size, by what factor does the width of the central diffraction maximum change?
A) Decreases by a factor of four
B) Doubles
C) Halves
D) Increases four times

Question

Quizplus · Accepted Answer

The width of the central diffraction maximum is proportional to the width of the slit, according to the single-slit diffraction formula. Therefore, if the slit width is halved, the width of the central maximum will also be halved (since it is the same proportion). However, the intensity of the central maximum will quadruple, since the area of the slit has also been halved. Therefore, the correct answer is choice B, which reflects only the change in width, not intensity.

Light Is Shone Through an Adjustable-Width Slit in an Otherwise