Dual Nature Of Light Question 394
Question: In the photoelectric experiment, if we use a monochromatic light, the I-V curve is as shown. If work function of the metal is 2eV, estimate the power of light used. (Assume efficiency of photo emission $ {{10}^{-3}}% $ , i.e., number of photoelectrons emitted are $ {{10}^{-3}}% $ of number of photons incident on metal)
Options:
A) 2W
B) 5W
C) 7W
D) 10W
Show Answer
Answer:
Correct Answer: C
Solution:
[c] The energy of incident photons is given by $ hv=eV_{s}+{\phi_{0}}=2+5=7eV $ ( $ V_{s} $ is stopping potential and $ {\phi_{0}} $ is work function) Saturation current $ ={{10}^{-5}}A $ $ =\frac{\eta P}{hv}e=\frac{{{10}^{-5}}P}{7\times e}e $ ( $ \eta $ is photon emission efficiency)
$ \therefore P=7W $
BETA
