Light is incident on a metallic plate having work function $110 imes 10^{-20} \mathrm{~J}$. If the

Question

Light is incident on a metallic plate having work function $110 	imes 10^{-20} \mathrm{~J}$. If the produced photoelectrons have zero kinetic energy then the angular frequency of the incident light is $\_\_\_\_$ $\mathrm{rad} / \mathrm{s}$. $\left(\mathrm{h}=6.63 	imes 10^{-34} \mathrm{~J} . \mathrm{s}ight)$.

Professor PC Thomas Classes · Answer

According to Einstein's photoelectric equation, $K_{max} = h
u - \phi$. If the maximum kinetic energy is zero, the energy of the incident photon exactly matches the work function: $h
u = \phi \Rightarrow \frac{h}{2\pi}\omega = \phi$. Solving for angular frequency: $\omega = \frac{2\pi\phi}{h} = \frac{2 	imes 3.14 	imes 110 	imes 10^{-20}}{6.63 	imes 10^{-34}} \approx \frac{690.8 	imes 10^{-20}}{6.63 	imes 10^{-34}} \approx 104 	imes 10^{14} 	ext{ rad/s} = 1.04 	imes 10^{16} 	ext{ rad/s}$.