Radiation, with wavelength 6561 Å falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3 × 10 - 4 T . If the radius of the largest circular p

Question

Radiation, with wavelength 6561 Å falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of 3 × 10 - 4 T . If the radius of the largest circular path followed by the electrons is 10 m m , the work function of the metal is close to:

TestHub · Accepted Answer

K E m a x = E - ϕ = 12400 λ i n Å - ϕ (in eV) ∴ r = 2 m K E e B K E m a x = r 2 e 2 B 2 2 m (in J) = r 2 e B 2 2 m (in eV) ∴ ϕ = 12400 6556 - r 2 e B 2 2 m = 1.1 e V

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