The work function of a metal is 4 eV. What should be the wavelength of the incident radiation for the emission of photoelectrons of zero velocity ?

Options

A. 2500 Å
B. 3100 Å
C. 3500 Å
D. 3800 Å

Answer

B

Explanation

For photo emission `hv=(hc)/(lambda)=W_(0)+E_(K)` but in this case
`E_(K)=0` as the velocity is zero.
`:.(hc)/(lambda)=W_(0)`
`:.lambda=(hc)/(W_(0))=(6.63xx10^(-34)xx3xx10^(8))/(4xx1.6xx10^(-19))`
`=(6.63xx3)/(6.4)xx10^(-7)`
`=3.1xx10^(-7)xx10^(10)Å=3100 Å`