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A light beam of wavelength 500 nm is incident on a metal having work function of 1 . 25 eV , placed in a magnetic field of intensity B . The electrons emitted perpendicular to the magnetic field B , with maximum kinetic energy are bent into a circular arc of radius 30 cm . The value of B is ________ × 10 - 7 T . Given h c = 20 × 10 - 26 J m , the mass of the electron = 9 × 10 - 31 kg .

Correct answer

0

Step-by-step solution

By photoelectric equation h c λ - ϕ = k max k max = 1240 500 - 1 . 25 ≈ 1 . 25 r = 2 m k e B B = 2 m k e r = 125 × 10 - 7   T

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