From the Einstein's photoelectric equation K=λhc−ϕ⇒ϕ=λhc−K
Now R=Bqmv⇒v=mRBq⇒K=2mR2B2q2
Therefore, ϕ=λhc−2mR2B2q2=4500×10−106.63×10−34×3×108−2×9.1×10−31(2×10−3×2×10−3×1.6×10−19)2⇒ϕ=(4.42−2.25)×10−19J=1.62.27eV=1.36eV
JEE Main 2022 — Physics Electromagnetism
A metal surface is illuminated by a radiation of wavelength 4500A∘. The ejected photo-electron enters a constant magnetic field of 2mT making an angle of 90∘ with the magnetic field. If it starts revolving in a circular path of radius 2mm, the work function of the metal is approximately
Held on 26 Jun 2022 · Verified 6 Jul 2026.
1.36eV
1.69eV
2.78eV
2.23eV
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