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NEET 2017 ((one Or More Correct)) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from NEET 2017 ((one Or More Correct))

Q138NEET 2017 · (One or more correct)Medium

Photoelectric Effect: Einstein's Equation

The photoelectric threshold wavelength of silver is 3250 ×\times 10−-10 m. The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 ×\times 10−-10 m is {Given h = 4.14 ×\times 10−-15 eV s and c = 3 ×\times 108 m s−1{}^{-1} ]

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Answer: (a)

  1. hc=4.14×10−15×3×108=1.242×10−6hc = 4.14 \times 10^{-15} \times 3 \times 10^{8} = 1.242 \times 10^{-6} eV m
  2. E=1.242×10−62536×10−10=4.90E = \frac{1.242 \times 10^{-6}}{2536 \times 10^{-10}} = 4.90 eV, ϕ=1.242×10−63250×10−10=3.82\phi = \frac{1.242 \times 10^{-6}}{3250 \times 10^{-10}} = 3.82 eV
  3. K=1.08K = 1.08 eV =1.72×10−19= 1.72 \times 10^{-19} J
  4. v=2×1.72×10−199.1×10−31≈6.1×105v = \sqrt{\frac{2 \times 1.72 \times 10^{-19}}{9.1 \times 10^{-31}}} \approx 6.1 \times 10^{5} m/s
  5. So the answer is (a) ≈0.6×106\approx 0.6 \times 10^{6} m/s.
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