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A beam of electromagnetic radiation comp...

A beam of electromagnetic radiation comprised of wavelength 620 nm on a perfectly absorbing metal (work function, `phi=2eV)` surface of area `1cm^2` Pressure exerted by the radiation on the surface is `3xx2^(-13)N//cm^3` . If one in `3xx10^3`photons ejects an electron, and total number of electrons ejected in 1 is `10^x`, then x is _______
[Given : hc=1240 e Vnm, 1eV=`1.6xx10^(-19)J]`

Text Solution

Verified by Experts

The correct Answer is:
A
No. of photons incident in 1 sec.
`N=(IA)/(((hc)/(lamda)))=(PC.A)/((hc)/(lamda))` where P is pressure.
`=(3.2xx10^(-13)xx3xx10^(8)xx1)/(((1240)/(620))xx1.6xx10^(-19))=3xx10^(14)`
`therefore` No. of electrons ejected are `(3xx10^(14))/(3xx10^(3))=10^(11)`
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