A beam of electromagnetic radiation of intensity 6.4 × 10 − 5 W / cm 2 is comprised of wavelength…

A beam of electromagnetic radiation of intensity 6.4× 10 −5 W/ cm 2 is comprised of wavelength, λ=310nm . It falls normally on a metal (work function φ=2eV ) of surface area of 1cm2 . If one in 103 photons ejects an election, total number of electrons ejected in 1s is 10x . hc=1240eVnm,1eV=1.6×10-19J, then x is ___________

Solution

Energy of photon. E=1240310 nm=4eV>2eV (So photoelectric effect will take place)
=4×1.6×10-19=6.4×10-19joule
Number of photons falling per second
=6.4×10-5×16.4×10-19=1014
Number of photoelectron emitted per second
=1014103=1011

Asked in: JEE Main 2020 (07 Jan Shift 1)

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