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NEET 2012 (AIPMT, Prelims) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from NEET 2012 (AIPMT, Prelims)

Q152NEET 2012 · AIPMT · PRELIMSMedium

Photoelectric Effect: Einstein's Equation

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

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Answer: (c)

  1. n=2→1n = 2 \to 1: E=13.6(1−14)=10.2E = 13.6\left(1 - \frac{1}{4}\right) = 10.2 eV.
  2. ϕ=10.2−3.57=6.63\phi = 10.2 - 3.57 = 6.63 eV =6.63×1.6×10−19= 6.63 \times 1.6 \times 10^{-19} J
  3. ν0=ϕh=6.63×1.6×10−196.63×10−34=1.6×1015\nu_0 = \frac{\phi}{h} = \frac{6.63 \times 1.6 \times 10^{-19}}{6.63 \times 10^{-34}} = 1.6 \times 10^{15} Hz
  4. So the answer is (c).
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