Verified Solution • 2025–26 Session moderate

QJEEM22Ph9f7b: JEE Main 2022 Physics - Class 12 JEEM22Ph9f7b Solution: A metal surface is illuminated by a radiation of wavelength…

A metal surface is illuminated by a radiation of wavelength 4500 Ao\mathop A\limits^o . The ejected photo-electron enters a constant magnetic field of 2 mT making an angle of 90 ∘^\circ with the magnetic field. If it starts revolving in a circular path of radius 2 mm, the work function of the metal is approximately :

Multiple Choice Options

  • A 1.36 eV
  • B 1.69 eV
  • C 2.78 eV
  • D 2.23 eV

Step-by-Step Verified Solution

hcλ−ϕ=KE{{hc} \over \lambda } - \phi = KE ...... (i)

R=mvBq=2m(KE)BqR = {{mv} \over {Bq}} = {{\sqrt {2m(KE)} } \over {Bq}} ...... (ii)

Putting the values,

ϕ≃1.36\phi \simeq 1.36 eV

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