Modern Physics Ques 83
- For photo-electric effect with incident photon wavelength $\lambda$, the stopping potential is $V _0$. Identify the correct variation(s) of $V _0$ with $\lambda$ and $\frac{1}{\lambda}$.
(2015 Adv.)
(a)
(b)
(c)
(d)
Show Answer
Answer:
Correct Answer: 83.(a,c)
Solution:
Formula:
$ \begin{aligned} e V _0 & =\frac{h c}{\lambda}-W \\ V _0 & =(\frac{h c}{e} )(\frac{1}{\lambda})-\frac{W}{e} \end{aligned} $
$V _0$ versus $\frac{1}{\lambda}$ graph is in the form $y=m x-c$
Therefore option (c) is correct.
Clearly, $V _0$ versus $\lambda$ graph is not a straight line but $V _0$ decreases with increase in $\lambda$ and $V _0$ becomes zero when $\frac{h c}{\lambda}=W$.
$ \text { i.e. } $ $\quad \lambda=\lambda _0$
(Threshold wavelength)
$\therefore$ Option (a) is also correct.
BETA
