The photoelectric work function for a metal surface is 4.125eV. The cut -off wavelength for this surface is

Options

A. 4125Å
B. 2062.5Å
C. 3000Å
D. 6000Å

Answer

C

Explanation

Work function ,w=4.125eV
The expression for cut- off wavelength is given as ,
`lamda=(hc)/(w)`
`implieslamda=((6.6xx10-^(34))xx(3xx10^(8)))/(4.125xx1.6xx10^(19))(becauseh=6.6xx10^(34)`
`c=3xx10^(8))`
`(6.6xx3xx10^(-7))/(4.125xx1.6)`
`3xx10^(-7)m`
`thereforelamda=3000A^(o)`