The magnetic field associated with a light wave is given, at the origin, by B = B 0 sin ⁡ 3.14 × 10 7 c t +…

The magnetic field associated with a light wave is given, at the origin, by B=B0 sin3.14×107ct+sin6.28×107ct. If this light falls on a silver plate having a work function of 4.7eV, what will be the maximum kinetic energy of the photoelectrons?

(c=3×108ms1,h=6.6×1034Js)
  1. 6.82 eV
  2. 7.72 eV
  3. 12.5 eV
  4. 8.52 eV

Solution

B=B0sin3.14×107ct+sin6.28×107ct

Maximum KE will associate with the maximum frequency

fmax =6.28×107c2π=107×3×108 Hz           =3×1015 Hz

KEmax=hfmax-ϕ

=6.63×10-34×3×10151.6×10-19-4.7 eV

=7.72 eV

Asked in: JEE Main 2019 (09 Jan Shift 2)

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