Question

The work functions for metals $A,B$ and $C$ are respectively $1.92eV,2.0eV$ and $5eV$. According to Einstein's equation, the metals which will emit photoelectrons for radiation of wavelength 4100 $\mathring{A}$ is/are:

• A. None
• B. A only
• C. A and B only
• D. All the three metals

Answer 1

The correct option is C A and B only

Work function for A, B and C metal are:

$A_0\left(A\right)=1.92eV,A_0\left(B\right)=2.0eV,A_0\left(C\right)=5eV$

The energy corresponding to the irradiated light is

$E=hc/\lambda =\frac{12400eV\mathring{A}}{4100\mathring{A}}\approx 3eV$

Metals having a work function less than the energy of radiated light will emit electron.

Metal C has a higher work function than the energy of the incident light.

Hence only A and B metals can emit photoelectrons.

Option C is correct