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JEE Main 2023 (13 Apr, Shift 1) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from JEE Main 2023 (13 Apr, Shift 1)

Q72JEE Main 2023 · 13 APR · SHIFT 1Easy

Photoelectric Effect: Einstein's Equation

The difference between threshold wavelengths for two metal surfaces A\text{A} and B\text{B} having work function ϕA=9 eV\phi_A = 9\text{ eV} and ϕB=4.5 eV\phi_B = 4.5\text{ eV} in nm\text{nm} is:

{\{ Given, hc =1242 eVnm}= 1242\text{ eVnm}\}

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Answer: (b)

  1. λ0=hcϕ\lambda_0 = \dfrac{hc}{\phi}
  2. λA=12429=138 nm\lambda_A = \dfrac{1242}{9} = 138\text{ nm}, λB=12424.5=276 nm\lambda_B = \dfrac{1242}{4.5} = 276\text{ nm}
  3. Difference =276−138=138 nm= 276 - 138 = 138\text{ nm}
  4. So the answer is (b) 138.
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