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 electron is increased which of the following statements is correct?

Options

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

Answer

A

Explanation

Wavelength of electron
`lambda=(h)/(mv)`
`:. Lambda prop (1)/(v)` h and m is constant
As speed is increased so wavelength will decreases and diffraction depend on `sin theta prop lambda`, as decrease sine also decreases, so `theta` decreases. As a result angular width decreases.