Question

Graph of cut-off potential $\left(V_0\right)$ versus frequency $(f)$ for same intensity of light for metal plates $A$ and $B$ are as shown in the figure below. Choose the correct statement.

• A. Work function of metal $A$ is greater than work function of metal $B$
• B. Work function of metal $A$ is less than work function of metal $B$
• C. Work function of metal $A$ is equal to work function of metal $B$
• D. Both line have same intercept

Answer 1

Answer: (B)

$hf=h{f}_0+e{V}_0$
$\therefore e{V}_0=hf-h{f}_0$
$V_0=\frac{hf}{e}-\frac{h{f}_0}{e}$
As ${\left(\text{Intercept}\right)}_B>{\left(\text{Intercept}\right)}_A$
${\left(\frac{h{f}_0}{e}\right)}_B>{\left(\frac{h{f}_0}{e}\right)}_A$
$\therefore {\varphi }_A<{\varphi }_B$