Physics Circle home Student Login

Home›Chapters›Dual Nature of Radiation and Matter PYQs›Photoelectric Effect: Einstein's Equation›Question 151

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

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

Q151NEET 2012 · AIPMT · MAINSEasy

Photoelectric Effect: Einstein's Equation

Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitive metallic surface of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons is

Show answer and solution

Answer: (b)

  1. Einstein's equation: 12mvmax2=E−ϕ\frac{1}{2}mv_{max}^2 = E - \phi, so vmax∝E−ϕv_{max} \propto \sqrt{E - \phi}.
  2. K1=1−0.5=0.5K_1 = 1 - 0.5 = 0.5 eV, K2=2.5−0.5=2K_2 = 2.5 - 0.5 = 2 eV
  3. v1v2=0.52=12\frac{v_1}{v_2} = \sqrt{\frac{0.5}{2}} = \frac{1}{2}
  4. So the answer is (b) 1:21:2.
Report a mistake

More questions on Photoelectric Effect: Einstein's Equation