Q.
Light of wavelength 5000A˚ and intensity 39.8Wm−2 is incident on a metal surface. If only 1% photons of incident light emit photoelectrons, then the number of electrons emitted per second per unit area from the surface will be nearly
2184
204
Dual Nature of Radiation and Matter
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Solution:
Energy of photon E=λhc=500nm1242eV−nm=2.484eV =2.484×1.6×10−19J=4×10−19J Intensity =39.8m2W=m239.8J/s
Number of photons falling per second per unit area =4×10−19(m2s)39.8(JJ)=1×1020 1% of photon eject photoelectron =1%×1020=1018