$A$ zinc ball of radius $1 \,cm$ is charged to a potential of $-0.5 \,V$. The ball is illuminated by a monochromatic ultraviolet light with a wavelength of $290 \,nm$. The photoelectric threshold for zinc is $332 \,nm$. The potential of the ball after a prolonged exposure to the ultraviolet light is ............. $V$.

$A$ photoelectric surface is illuminated successively by monochromatic light of wavelength $\lambda$ and $\frac{\lambda}{2}$. If the maximum kinetic energy of the emitted photoelectrons in the first case is one-third that in the second case,the work function of the surface of the material is ($c=$ speed of light,$h=$ Planck's constant).

The work functions of metals are given as $Na = 1.92 \, eV$,$K = 2.15 \, eV$,$Mo = 4.17 \, eV$,and $Ni = 5.0 \, eV$. Which of these metals will not show photoelectric emission for radiation of wavelength $3300 \, \mathring{A}$ from a $He-Cd$ laser?

What is zero-point energy or Fermi energy?

When ultraviolet rays are incident on a metal plate, the photoelectric effect does not occur. It occurs by the incidence of:

The threshold frequency of a photosensitive material is equal to the frequency of the $H_{\alpha}$ line of hydrogen. If a photon whose frequency is equal to the frequency of the $H_{\beta}$ line of hydrogen is incident on this photosensitive material,the maximum kinetic energy of the emitted photoelectrons is ($R$ = Rydberg's constant,$h$ = Planck's constant,and $c$ = speed of light in vacuum).