Question

If the frequency of light incident on metal surface is doubled, then kinetic energy of emitted electron will become

• A. doubled
• B. less than double
• C. more than double
• D. nothing can be said

Answer 1

Answer: (C)

From Einstein's photoelectric equation,
we have $E_k=hv-W$
where $E_k$ is maximum kinetic energy of photoelectrons and $W$ the work function
$\left(=h{v}_0\right)$.
$\therefore E_k=h\left(v-v_0\right)$ ..(i)
where $v_0$ is threshold frequency.
For $h{v}^{\prime }=2hv$
$\therefore 2E_k=2h\left(v-v_0\right)$..(ii)
From Eqs. (i) and (ii),
we observe that kinetic energy of emitted electron will become more than doubled.