Question

Two light beams of frequencies $2v_0$ and $3v_0$ and intensities $I_1$ and $I_2$ are incident on a metal surface having threshold frequency $v_0$. The ratio of maximum K.E. of photo electrons is ____________.

• A. $\frac{2}{3}$
• B. $\frac{1}{2}$
• C. $\frac{3}{2}$
• D. $\frac{I_1}{I_2}$

Answer 1

The correct option is B $\frac{1}{2}$

$KE=h\upsilon -h{\upsilon }_0$

$\frac{{KE}_1}{{KE}_2}=\frac{h{\upsilon }_1-h{\upsilon }_0}{h{\upsilon }_2-h{\upsilon }_0}=\frac{h{\times 2\upsilon }_0-h{\upsilon }_0}{h{\times 3\upsilon }_0-h{\upsilon }_0}=\frac{h{\upsilon }_0}{2h{\upsilon }_0}=\frac{1}{2}$