# The work functions for metals A, B and C are respectively $1.92\: eV, 2\: eV \: and \: 5 \: eV$. According to Einstein’s equation, the metals which will emit photoelectrons for a radiation of wavelength $4100\: A^{\circ}$ is / are

$\begin {array} {1 1} (a)\;None & \quad (b)\;A\: only \\ (c)\;A\: and \: B \: only & \quad (d)\;all\: the\: three \: metals \end {array}$

Ans : (c) A and B only
Energy in $eV = 12375/wavelength\: in\: A^{\circ} = 12375 / 4100 = 3$
The work functions for A and B are less than $3\: eV$. So, A and B will emit
photoelectrons. But since work function of /c is more than $3\: eV$,
so it will not emit.

edited Mar 13, 2014