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The magnetic field associated with a light wave is given, at the origin, by B = B 0 sin ⁡ 3.14 × 10 7 c t + sin ⁡ 6.28 × 10 7 c t . If this light falls on a silver plate having a work function of 4 .7 eV , what will be the maximum kinetic energy of the photoelectrons? ( c = 3 × 10 8 m s − 1 , h = 6 .6 × 10 − 34 J s )

Options

  1. A6 .82   eV
  2. B7 .72 eV
  3. C12 .5   eV
  4. D8 .52   eV

Correct answer

B. 7 .72 eV

Step-by-step solution

B = B 0 sin ⁡ 3.14 × 10 7 c t + sin ⁡ 6.28 × 10 7 c t Maximum K E will associate with the maximum frequency f max ⁡   = 6.28 × 10 7 c 2 π = 10 7 × 3 × 10 8   Hz                       = 3 × 10 15   Hz K E m a x = h f m a x - ϕ = 6 .63 × 10 - 34 × 3 × 10 15 1 .6 × 10 - 19 - 4 .7   eV = 7 .72   eV

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