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# In an experiment on photoelectric effect, the separation between emitter and the collector plates is 10cm. Plates are connected through an ammeter without any cell. A magnetic field B exists parallel to the plates. The work function of the emitter is 2.39eV and the light of wavelengths between 400nm and 600nm is incident on it. If minimum value of B for which the current registered by the ammeter is zero is n×10−6T. Then find out value of n (Neglect any effect of space charge). (assume emission of photo electron to be radomly every possible direction) Open in App
Solution

## Here; Φ0=2.39eVλ1=400nm and λ2=600nmFor ′B′ to be minimum Energy should be Maximum∴ λ sgould be minimumHere; E=hcλ−Φ0 =3.015−2.39 =0.715eVThe presence of M.field will bend the beam there will be no current if the electron does'not reach the other plates.∴r=mvqB⇒r=√2mEqB⇒B=√2×9.1×10−31×1.6×10−19×0.7151.6×10−19×0.1=2.85×10−5=0.285×10−6Tesla   Suggest Corrections  0      Related Videos   The Experimental Setup
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