Dual Nature Of Light Question 107
Question: A silver ball of radius 4.8 cm is suspended by a thread in the vacuum chamber. UV light of wavelength 200 nm is incident on the ball for some times during which a total energy of 1 ´ 10?7 J falls on the surface. Assuming on an average one out of 103 photons incident is able to eject electron. The potential on sphere will be
Options:
A) 1 V
B) 2 V
C) 3 V
D) Zero
Show Answer
Answer:
Correct Answer: C
Solution:
$ n=\frac{E\lambda }{hc} $ $ =\frac{1\times {{10}^{-7}}\times 200\times {{10}^{-9}}}{6.6\times {{10}^{-34}}\times 3\times 10^{8}}=1\times 10^{11} $ Number of electrons ejected $ =\frac{10^{11}}{10^{3}}=10^{8} $ \ $ V=\frac{q}{4\pi {\varepsilon_{0}}r}=\frac{(10^{8}\times 1.6\times {{10}^{-19}})\times 9\times 10^{9}}{4.8\times {{10}^{-2}}}=3,V $
BETA
