Q156 / 160 · TS EAMCET 2004 · Physics
Electrons ejected from the surface of a metal, when light of certain frequency is incident on it, are stopped fully by a retarding potential of 3 volts. Photoelectric effect in this metallic surface begins at a frequency $6 \times 10^{14} \mathrm{~s}^{-1}$. The frequency of the incident light in $\mathrm{s}^{-1}$ is : [Planck's constant $=6.4 \times 10^{-34} \mathrm{Js}$, charge on the electron $\left.=1.6 \times 10^{-19} \mathrm{C}\right]$
- A$7.5 \times 10^{13}$
- B$13.5 \times 10^{13}$
- Correct answerC$13.5 \times 10^{14}$
- D$7.5 \times 10^{15}$
Solution
Einstein's photoelectric equation is given by
$$
\begin{aligned}
h v & =h v_0+\phi=h v_0+e V \\
\Rightarrow \quad v & =v_0+\frac{e V_0}{h}=\left(6 \times 10^{14}\right)+\frac{\left(1.6 \times 10^{-19}\right)(3)}{\left(6.4 \times 10^{-34}\right)} \\
& =13.5 \times 10^{14} s^{-1}
\end{aligned}
$$
Hence, the correct answer is option: 'C'.