Physics - Modern Physics Question with Solution | TestHub

The threshold wavelength ${\lambda }_0$ is given by ${\lambda }_0=\frac{hc}{\Phi }$.

Substituting the given values:

${\lambda }_0=\frac{6.6\times 10^{-34}\times 3\times 10^8}{6.6\times 1.6\times 10^{-19}}$

${\lambda }_0=\frac{3}{1.6}\times 10^{-7}$ m

${\lambda }_0=1.875\times 10^{-7}$ m $=187.5$ nm

For the photoelectric effect to take place, the wavelength of incident radiation must be less than or equal to the threshold wavelength ($\lambda \le {\lambda }_0$).

Among the given options, $200$ nm is greater than $187.5$ nm.

Thus, radiation of wavelength $200$ nm will not give rise to the photoelectric effect.

Answer: $200$ nm