Question

Any radiation in the ultra violet region of Hydrogen spectrum is able to eject photoelectrons from a metal. Then the threshold frequency of the metal for a threshold $\lambda =\frac{1}{R}=911\dot{A}$,is nearly

• A. $3.3\times {10}^{15}HZ$
• B. $2.5\times {10}^{15}HZ$
• C. $4.6\times {10}^{14}HZ$
• D. $8.2\times {10}^{14}HZ$

Answer 1

The correct option is A $3.3\times {10}^{15}HZ$

$c=\nu \lambda$ ; $\nu =\frac{c}{\lambda }=\frac{3\times {10}^8}{911\times {10}^{-10}}$
$\nu =3.3\times {10}^{15}HZ$