question_answer

A beam of light has two wavelengths of \[\text{4972}\overset{\text{o}}{\mathop{\text{A}}}\,\] and \[6216\overset{\text{o}}{\mathop{\text{A}}}\,\] with a total intensity of \[3.6\times {{10}^{-3}}W{{m}^{-2}}\] equally distributed among the two wavelengths. The beam falls normally on an area of \[1c{{m}^{2}}\] of a clean metallic surface of work function 2.3eV. Assume that there is no loss of light by reflection and that each capable photon ejects one electron. The number of photoelectrons liberated in 2s is approximately.

A) \[6\times {{10}^{11}}\]

B) \[9\times {{10}^{11}}\]

C) \[11\times {{10}^{11}}\]

D) \[15\times {{10}^{11}}\]