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MHT CET 2024 (10 May, Shift 2) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from MHT CET 2024 (10 May, Shift 2)

Q62MHT CET 2024 · 10 MAY · SHIFT 2Medium

Photoelectric Effect: Einstein's Equation

A photoelectric surface is illuminated successively by monochromatic light of wavelength ' λ\lambda ' and (λ2)\left(\frac{\lambda}{2}\right). If the maximum kinetic energy of the emitted photoelectrons in the first case is one-fourth that in the second case, the work function of the surface of the material is ( c=c = speed of light, h=h = Planck's constant))

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Answer: (c)

  1. K1=hcλ−ϕK_1 = \frac{hc}{\lambda} - \phi, K2=2hcλ−ϕK_2 = \frac{2hc}{\lambda} - \phi, with K2=4K1K_2 = 4K_1
  2. 2hcλ−ϕ=4hcλ−4ϕ⇒3ϕ=2hcλ\frac{2hc}{\lambda} - \phi = \frac{4hc}{\lambda} - 4\phi \Rightarrow 3\phi = \frac{2hc}{\lambda}
  3. ϕ=2hc3λ\phi = \frac{2hc}{3\lambda}. So the answer is (c).
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