Question

A parallel beam of fast-moving electrons is incident perpendicular on a narrow slit. The distance between slit and screen is large. If the speed of the incident electrons is increased then which one of the following statements is correct?

Options

• The angular width of the central maximum will decrease.

• The angular width of the central maximum will remain the same.

• The diffraction pattern is not observed on the screen in the case of electrons.

• The angular width of the central maximum of the diffraction pattern will increase.

Answer 1

The angular width of the central maximum will decrease.

Explanation:

`lambda = h/(mv)`

∴ If v increases λ will decrease.

Angular width = `(2lambda)/d`

∴ Angular width will decrease.