Q 12-14-060JEE MainJEE Main 2024 (1 Feb, Shift 2)Easy
The conductivity of a photodiode starts changing only if the wavelength of the incident light is less than $660\ \text{nm}$. The band gap of the photodiode is found to be $\dfrac{X}{8}\ \text{eV}$. The value of $X$ is (Given $h = 6.6\times10^{-34}\ \text{J s}$, $e = 1.6\times10^{-19}\ \text{C}$)
Answer: (A) $15$
$$E_g = \frac{hc}{\lambda} = \frac{6.6\times10^{-34}\times3\times10^8}{660\times10^{-9}} = 3\times10^{-19}\ \text{J} = \frac{3\times10^{-19}}{1.6\times10^{-19}}\ \text{eV} = \frac{15}{8}\ \text{eV}$$
So $X = 15$.
Solution by Sreeraj P, M.Sc Physics