There are two black bodies A and B with temperatures 1500 k and 3600 k respectively . Photons having wavelength equal to the wavelength corresponding to maximum spectral radiancy of A & B (say lambda_A and lambda_B respectively) are incident on a metal sphere of radius 12 cm having work-function 1.2 eV. The maximum kinetic energies of the electrons emitted by these photons are in the ratio 1:3 . Find the wavelengths lambda_A and lambda_B. if 10^(12) photons of wavelength lambda_B are incident per second and photo electric efficiency is one electron per 10^6 photons , find the time after which emission of photo-electrons will stop. in this case assume that lambda_A is not present.

There are two black bodies A and B with temperatures 1500 k and 3600 k

1.	There are two black bodies A and B with temperatures 1500 k and 3600 k respectively . Photons having wavelength equal to the wavelength corresponding to maximum spectral radiancy of A & B (say lambda_A and lambda_B respectively) are incident on a metal sphere of radius 12 cm having work-function 1.2 eV. The maximum kinetic energies of the electrons emitted by these photons are in the ratio 1:3 . Find the wavelengths lambda_A and lambda_B. if 10^(12) photons of wavelength lambda_B are incident per second and photo electric efficiency is one electron per 10^6 photons , find the time after which emission of photo-electrons will stop. in this case assume that lambda_A is not present.
Answer» SOLUTION :`lambda_b=(12375)/(9.6)A=1289A,lambda_a=3093.75a,t=700 "SEC"`

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