Question

The beam of light has wavelengths \(4144\,\text{\AA}\), \(4972\,\text{\AA}\), and \(6216\,\text{\AA}\) with a total intensity of \(3.6 \times 10^{-3}\,\text{W m}^{-2}\) equally distributed among the three wavelengths. The beam falls normally on an area of \(1\,\text{cm}^2\) of a clean metallic surface of work function \(2.3\,\text{eV}\). Assume that there is no loss of light by reflection and that each energetically capable photon ejects one electron. Calculate the number of photoelectrons liberated in \(2\,\text{s}\).

• A. \(2\times10^9\)
• B. \(1.075\times10^{12}\)
• C. \(9\times10^8\)
• D. \(3.75\times10^6\)

Hint:

Only photons with: \[ h\nu \ge \phi \] contribute to photoelectric emission.

Answer 1

The Correct Option is B