question_answer

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

A) \[\text{4 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{15}}}\,{{\text{H}}_{\text{Z}}}\]                          

B) \[\text{5 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{15}}}\,{{\text{H}}_{\text{Z}}}\]          

C)        \[\text{1}\text{.6 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{15}}}\,{{\text{H}}_{\text{Z}}}\]         

D)        \[\text{2}\text{.5 }\!\!\times\!\!\text{ 1}{{\text{0}}^{\text{15}}}\,{{\text{H}}_{\text{Z}}}\]