Question

If threshold frequency of a metal surface is $7\times {10}^{14}\text{Hz}$, find the work function of the metal.

• A. $2.2\text{eV}$
• B. $4.6\text{eV}$
• C. $2.9\text{eV}$
• D. $9.2\text{eV}$

Answer 1

The correct option is C $2.9\text{eV}$

Work function = ${\varphi }_0=\frac{h{f}_0}{e}$

${\varphi }_0=\frac{6.63\times {10}^{-34}\times 7\times {10}^{14}}{1.6\times {10}^{-19}}$

${\varphi }_0=2.896\text{eV}\approx 2.9\text{eV}$

Hence, $\left(C\right)$ is the correct answer.

Why this question? concept: ${\varphi }_0=h{f}_0$ --(in $\text{J}$) work function: ${\varphi }_0=\frac{hf{}_0}{e}$ ---(in $\text{eV}$)