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).

10 W

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The correct Answer is:

The energy of incident photosn 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^(-6) A=(etaP)/(hv) e =(10^(-5)P)/(7xxe) e` (`eta` is photo emission efficiency)
`:. P=7W`.

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