Question

The thershold frequency for caesium metal is $5.16\times {10}^{14}$Hz. Determine its work function in eV.

Answer 1

The threshold frequency is the minimum frequency of photon required that would cause ejection of photo electron.
The work function of metal is the minimum energy required by metal to cause ejection of electron from its surface.
They are related as

$W_0=h\nu$

$=6.626\times {10}^{-34}\times 5.16\times {10}^{14}J$

$=2.13eV$