Question

For photoelectric emission from certain metal, the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) ____________.

Options

• `sqrt("hv"/"(2m)")`

• `sqrt("hv"/"m")`

• `sqrt("2hv"/"m")`

• `2sqrt("hv"/"m")`

Answer 1

For photoelectric emission from certain metal, the cut-off frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (mis the electron mass) `sqrt("2hv"/"m")`.

Explanation:

Cut-off frequency is given as v

Work function `phi` = hv

Now, E = K.E. + `phi`

2hv = `1/2`mv² + hv

`therefore 1/2`mv² = 2hv - hv

`therefore 1/2`mv² = hv

`therefore  "v" = sqrt("2hv"/"m")`