The work function for metals A,B and C are respectively 1.92 eV, 2.0 eV and 5.0 eV. According to Einstein's equation, the metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are

Options

A. none of these
B. a only
C. A and B only
D. all the three metals.

Answer

C

Explanation

Energy of photon of radiation `4100Å=4.1xx10^(-7)m` in eV will be
`E=(hc)/(elamda)=(6.63xx10^(-34)xx3xx10^(8))/(1.6xx10^(-19)xx4.1xx10^(-7))=3.03eV`
As work functions for metals A and B are 1.92 eV and 2.00 eV respectively and are less than the energy of incident photon, hence metals A and B will emit photoelectrons.