In photoelectric effect, the stopping potential $(V_0)$ vs frequency $(\nu)$ curve is plotted ($h$ is the Planck's constant and $\phi_0$ is the work function of the metal).
(A) $V_0$ vs $\nu$ is linear.
(B) The slope of the $V_0$ vs $\nu$ curve $= \dfrac{\phi_0}{h}$.
(C) $h$ is related to the slope of the $V_0$ vs $\nu$ line.
(D) The value of the electric charge of the electron is not required to determine $h$ using the $V_0$ vs $\nu$ curve.
(E) The work function can be estimated without knowing the value of $h$.
Choose the correct answer from the options given below:
Answer: (B) (A), (C) and (E) only
Einstein's equation gives
$$eV_0 = h\nu - \phi_0 \Rightarrow V_0 = \frac{h}{e}\nu - \frac{\phi_0}{e}$$
- (A) Linear: correct.
- (B) The slope is $h/e$, not $\phi_0/h$: wrong.
- (C) The slope gives $h$ (as $h/e$): correct.
- (D) To get $h$ from the slope $h/e$ you need $e$: wrong.
- (E) The intercept on the $V_0$ axis is $-\phi_0/e$, so $\phi_0$ (in eV) is read off directly without $h$: correct.
(A), (C) and (E) only.
Solution by Sreeraj P, M.Sc Physics