In a photocell bi chromatic light of wave length 2480Å and 6000Å are incident on a cathode whose work function is 4.8eV. If a uniform magnetic field of 3xx10^(-5)T exists parallel to the plate, find the radius of the circular path described by the photoelectron. (mass of electron is 9xx10^(-31)kg)

In a photocell bi chromatic light of wave length 2480Å and 6000Å are

1.	In a photocell bi chromatic light of wave length 2480Å and 6000Å are incident on a cathode whose work function is 4.8eV. If a uniform magnetic field of 3xx10^(-5)T exists parallel to the plate, find the radius of the circular path described by the photoelectron. (mass of electron is 9xx10^(-31)kg)
Answer» Solution :`E_(1)=(12400)/(lamda_(1))=(12400)/(2480)=5eV` `E_(2)=(12400)/(lamda_(2))=(12400)/(6000)=2.06eV` As `E_(2)ltW_(0)` and `E_(1)gtW_(0)`,PHOTO ELECTRIC emission is possible only with `lamda_(1)`. Maximum K.E of emitted photo electrons `K=E_(1)-W_(0)=0.2eV`. Photo electrons experience magnetic force and move along a circular path of radius `r=(mv)/(Bq)=(SQRT(2mK))/(Bq)impliesr=5cm`.

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