Question

The threshold wavelength of lithium is 8000$A^0$. When light of wavelength 9000$A^0$ is made to be incident on it, then the photo electrons

• A. Will not be emitted
• B. Will be emitted
• C. Will sometimes be emitted and sometimes not
• D. Data insufficient

Answer 1

The correct option is A Will not be emitted

Answer is A.

$v\alpha \frac{1}{\lambda }$
$\therefore \lambda >{\lambda }_0$

$\Rightarrow \frac{hv}{\lambda }<\frac{hv}{{\lambda }_0}<h{c}_0$

$\therefore$ no emission occurs.