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?

de Broglie wavelength of an electron

$\lambda =\frac{h}{p}=\frac{h}{mv}$

where m is the mass and v is the speed of the electron respectively.

If speed v of electron is increased, momentum p (= mv) will increase. Hence, wavelength $\lambda$ will decrease.

Angular width of the central maximum is ${\theta }_0=\frac{2\lambda }{a}$where a is the width of slit.

If $\lambda$  decreases, ${\theta }_0$ will decrease