# A metal foil has a threshold frequency of 5.45× 1014 Hz. Which of the colors of visible light have enough energy to eject electrons from this metal?

## Red Orange Yellow Green Blue Indigo Violet

Nov 16, 2016

Einstein photoelectric equation

${E}_{k} = h \left(\nu - {\nu}_{o}\right)$

Where

${E}_{k} \to \text{Kinetic energy of ejected electron}$

$h \to \text{Planck's constant}$

$\nu \to \text{Frequency of incident radiation}$

${\nu}_{o} \to \text{Thresold Frequency of radiation}$

This equation reveals that ejection of electron from metal surface i.e KE of electron is possible iff $\nu > {\nu}_{o}$

Given

$\text{Thresold frequency} \left({\nu}_{o}\right) = 5.45 \times {10}^{14} H z$

As per above table the frequencies of Green,Blue,Indigo and Violet lights are greater than the thresold frequency. So those radiations are capable of ejecting electron from metal surface for having enough energy.