Atomic Structure 1 Question 5
5. Which of the graphs shown below does not represent the relationship between incident light and the electron ejected from metal surface?
(2019 Main, 10 Jan I)
(b)
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Answer:
Correct Answer: 5. (b)
Solution:
- For photoelectric effect,
$$ \mathrm{KE}=E-E_{0} $$
where,
$$ \begin{aligned} \mathrm{KE} & =\text { Kinetic energy of ejected electrons. } \ E & =\text { Energy of incident light }=h \nu \ E_{0} & =\text { Threshold energy }=h v_{0} \ v & =\text { Frequency of incident light } \ v_{0} & =\text { Threshold frequency } \end{aligned} $$
Slope $= \pm 1$, intercept $=-E_{0}$
So, option (a) is correct.
(ii) $\mathrm{KE}$ of ejected electrons does not depend on the intensity of incident light.
So, option (b) is correct.
(iii) When, number of ejected electrons is plotted with frequency of light, we get
So, option (c) is also correct.
(iv) $\mathrm{KE}=h v-h v_{0}$
Slope $=+h$, intercept $=-h v_{0}$. So, option (d) is not correct.
