Question

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $6800\stackrel{\circ }{A}$. Calculate threshold frequency $v_0$ and work function $w_0$ of the metal.

Answer 1

Since, K.E is zero, the energy of radiation is equal to the work function of the metal. Also, the threshold frequency is equal to the frequency of radiation.

The threshold frequency is

${\nu }_o=\nu =\frac{c}{\lambda }$

$=\frac{3.0\times {10}^{8}m/s}{6800\times {10}^{-10}}m$

$=4.41\times {10}^{14}/s$.

The work function is

$h{\nu }_0=6.626\times {10}^{-34}\times 4.41\times {10}^{14}$

$=2.92\times {10}^{-19}J$.