P-N Junction Diode and its applications: Practice Problem & Solution

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of P-N Junction Diode and its applications. Understanding the underlying formula is key to arriving at the correct answer below:

The maximum wavelength that can be detected is given by $\lambda = \frac{hc}{E_g}$. Substituting the values gives $\lambda = \frac{12400}{2.5} = 4960 \AA$. The photodiode can detect wavelengths less than this maximum limit, so $4000 \AA$ is the correct answer.