Question

The photo cut-off voltage in an experiment was found to be $1.5V$. The work function for the material used in the experiment was $4.2$ $2V$. The maximum kinetic energy for the photo electrons that was emitted was

• A. $1.5eV$
• B. $2.7eV$
• C. $4.2eV$
• D. $5.7eV$

Answer 1

The correct option is A $1.5eV$

Given, cut-off voltage , $V_0=1.5V$

We know that, the maximum kinetic energy of photo electrons is given by , $K_{max}=e{V}_0=1.5eV$