When a high frequency electromagnetic radiation is incident on a metallic surface, electrons are emitted from the surface. Energy of emitted photoelectrons depends only on the frequency of incident electromagnetic radiation and the number of emitted electrons depends only on the intensity of incident light.
Einstein's protoelectron equation `[K_(max)=hv-phi]` correctly ecplains the PE, where `upsilon=` frequency of incident light and `phi=` work function.
Q. For photoelectric effect in a metal, the graph of the stopping potential `V_0` (in volt) versus frequency `upsilon` (in hertz) of the incident radiation is shown in Fig. The work function of the metal (in eV) is.

Options

A. 12.5
B. 14.5
C. 16.5
D. 18.5

Answer

C

Explanation

`eV_0=h(v-v_0)`
When `V_0=0`,`v=v_0`, the threshold frequency.
From the graph it follows that
`v_0=4xx10^(15)Hz`
Therefore, work function is
`phi=hv_0=6.6xx10^(-34)xx3xx10^(15)`
`=16.5eV`