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JEE Main 2022 (29 Jun, Shift 2) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from JEE Main 2022 (29 Jun, Shift 2)

Q93JEE Main 2022 · 29 JUN · SHIFT 2Medium

Photoelectric Effect: Einstein's Equation

The electric field at a point associated with a light wave is given by

E = 200 [sin (6 ×\times 1015)t + sin (9 ×\times 1015)t] Vm−1{}^{-1}

Given: h = 4.14 ×\times 10−-15 eVs

If this light falls on a metal surface having a work function of 2.50 eV, the maximum kinetic energy of the photoelectrons will be

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Answer: (d)

  1. Highest angular frequency ω=9×1015\omega = 9 \times 10^{15} rad/s gives the maximum KE: ν=ω2π=1.43×1015\nu = \frac{\omega}{2\pi} = 1.43 \times 10^{15} Hz.
  2. E=hν=4.14×10−15×1.43×1015=5.93E = h\nu = 4.14 \times 10^{-15} \times 1.43 \times 10^{15} = 5.93 eV
  3. Kmax=5.93−2.50≈3.42K_{max} = 5.93 - 2.50 \approx 3.42 eV
  4. So the answer is (d) 3.42 eV.
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