In the middle of depletion layer of reverse biased p-n junction:

The correct answer is Option (4) → Electric field is maximum

In a reverse-biased p–n junction, the depletion region widens and the electric field varies across it, being maximum at the junction (middle of the depletion layer) and decreasing towards the edges.

Why other options are incorrect:

• Potential (Options 1 & 3): The electric potential changes continuously across the depletion layer. It is not zero or maximum in the middle; rather, the potential barrier is highest across the entire junction, but the specific value at the center is an intermediate one.

• Electric Field is nearly zero (Option 2): This is the opposite of the truth. The field is zero at the neutral edges of the p and n regions, not in the middle of the junction.