The photoelectric effect is described as the ejection of electrons from the surface of a metal when :

When electromagnetic radiation of wavelength $300 \, nm$ falls on the surface of a metal,electrons are emitted with the kinetic energy of $1.68 \times 10^5 \, J \, mol^{-1}$. What is the minimum energy needed to remove an electron from the metal? $(h = 6.626 \times 10^{-34} \, J \, s, c = 3 \times 10^8 \, m \, s^{-1}, N_A = 6.022 \times 10^{23} \, mol^{-1})$

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $6800 \, \mathring{A}$. Calculate threshold frequency $(v_{0})$ and work function $(W_{0})$ of the metal.

The work functions of $Ag, Mg, K$ and $Na$ respectively in $eV$ are $4.3, 3.7, 2.25, 2.30$. When an electromagnetic radiation of wavelength of $300 \ nm$ is allowed to fall on these metal surfaces,the number of metals from which the electrons are ejected is $(eV = 1.6022 \times 10^{-19} \ J)$

The metal used for making radiation shield is

Photoelectric effect is the phenomenon in which