Dual Nature Of Radiation And Matter Ques 35
35. The threshold frequency for a photosensitive metal is $3.3 \times 10^{14}$ $ Hz$. If light of frequency $8.2 \times 10^{14} Hz$ is incident on this metal, the cut-off voltage for the photoelectric emission is nearly
[2011 M]
(a) $2 $ $V$
(b) $3 $ $V$
(c) $5 $ $V$
(d) $1 $ $V$
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Answer:
Correct Answer: 35.(a)
Solution:
- (a) K.E. $=h v-h v _{\text{th }}=eV_0 \quad (V_0=$ cut off voltage $)$
$ \begin{aligned} & \Rightarrow V_0=\frac{h}{e}(8.2 \times 10^{14}-3.3 \times 10^{14}) \\ & =\frac{6.6 \times 10^{-34} \times 4.9 \times 10^{14}}{1.6 \times 10^{-19}} \approx 2 V \end{aligned} $
BETA
