Q. A parallel beam of fast moving electrons is incident normally on a narrow slit. A screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statement is correct?
A) Diffraction pattern is not observed on the screen in the case of electrons
B) The angular width of the central maximum of the diffraction pattern will increase
C) The angular width of the central maximum will decrease
D) The angular width of the central maximum will remains the same
Explanation
(c) Angular fringe width is the ratio of fringe width to distance (D) of screen from the source $ie$,
$\theta = \frac{\beta}{D}$
As D is taken large, hence angular fringe width of the central maximum will decrease.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.