(a) What is meant by the terms:
(i) a full wave rectifier
(ii) a photodiode
(iii) a LED?
(b) Draw energy band diagrams of n-type and p-type semiconductors at temperature `T gt 0` K. Mark the donor and acceptor energy levels with their energies.

Explanation

### Step-by-Step Solution:

**(a) Definitions:**

1. **Full Wave Rectifier:**
- A full wave rectifier is an electronic device that converts alternating current (AC) into direct current (DC). It achieves this by utilizing both halves of the AC cycle, allowing current to flow in one direction regardless of the polarity of the input voltage. This results in a smoother DC output compared to half-wave rectification, which only uses one half of the AC cycle.

2. **Photodiode:**
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