A beam of light consisting of a mixture of red ( = 620 nm ), green ( = 500 nm ), and violet ( = 400 nm ) light is incident on a metal surface having a work function of 2.2 eV . The stopping potential required to reduce the photoelectric cur

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A beam of light consisting of a mixture of red ( = 620 nm ), green ( = 500 nm ), and violet ( = 400 nm ) light is incident on a metal surface having a work function of 2.2 eV . The stopping potential required to reduce the photoelectric current to zero is: (Take hc = 1240 eV nm )

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Correct answer: A. 0.9 V

The energy of an incident photon is given by E = hc . Calculating the photon energy for each color in the beam: For red light: E_R = 1240 620 = 2.0 eV For green light: E_G = 1240 500 = 2.48 eV For violet light: E_V = 1240 400 = 3.1 eV The work function of the metal is = 2.2 eV . Since E_R Both green and violet light have energies greater than the work function and will cause emission. The stopping potential V₀ is determined by the maximum kinetic energy of the emitted photoelectrons, which corresponds to the most e

A beam of light consisting of a mixture of red ( = 620 nm ), green ( = 500 nm ), and violet ( = 400 nm ) light is incident on a metal surface having a work function of 2.2 eV . The stopping potential required to reduce the photoelectric current to zero is: (Take hc = 1240 eV nm )

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