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In the photoelectric experiment, if we u...

In the photoelectric experiment, if we use a monochromatic light, the I – V curve is as shown. If work function of the metal is 2 eV, estimate the power of light used. (Assume efficiency of photo emission `=10^(-3)` i.e. number of photoelectrons emitted are `10^(-3)` times of number of photons incident on metal).

A

2W

B

5W

C

7W

D

10 W

Text Solution

Verified by Experts

The correct Answer is:
C
The energy of incident photons is given by
`hv=eV_(s)+phi_(0)=2+5=7 eV` (`V_(s)` is stopping potential and `phi_(0)` is work function)
Saturation current `=10^(-5) A =(etaP)/(hv)e=(10^(-5)P)/(7xxe) e` (`eta` is photo emission efficiency)
`:.P=7 W`
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