Question

A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?

• A. The angular width of central maximum will be unaffacted.
• B. Diffraction pattern is not observed on the screen in the case of electrons.
• C. The angular width of the central maximum of the diffraction pattern will increase.
• D. The angular width of the central maximum will decrease.

Answer 1

Answer: (D)

As speed of electrons is increased so wavelength of electrons will decreases. Therefore the angular width $(\propto \lambda)$ of the central maximum of diffrection pattern will decrease.