In a normal operation of a transistor,
(i) base-emitter junction is forward-biased
(ii) base-collector junction is forward-biased
(iii) base-emitter junction is reverse-baised
(iv) base-collector junction is reverse-biased

Options

A. (a), (b)
B. (b), (c )
C. (c ), (d)
D. (d), (a)

Answer

To solve the question regarding the normal operation of a transistor, we need to analyze the biasing of the junctions in a typical NPN transistor configuration.

### Step-by-Step Solution:

1. **Understanding the Transistor Structure**:
- A transistor consists of three regions: the emitter (E), base (B), and collector (C). In an NPN transistor, the emitter is n-type, the base is p-type, and the collector is n-type.

2. **Analyzing the Base-Emitter Junction**:
- The base-emitter junction is formed between the p-type base and the n-type emitter. For normal operation, this junction must be **forward-biased**.
- This means that the n-type emitter is connected to the negative terminal of the power supply, and the p-type base is connected to the positive terminal. This allows current to flow from the emitter to the base.

3. **Analyzing the Base-Collector Junction**:
- The base-collector junction is formed between the p-type base and the n-type collector. For normal operation, this junction must be **reverse-biased**.
- In this case, the n-type collector is connected to the positive terminal of the power supply, and the p-type base is connected to the negative terminal. This prevents current from flowing from the collector to the base.

4. **Conclusion**:
- Based on the analysis:
- The base-emitter junction is forward-biased (correct).
- The base-collector junction is reverse-biased (correct).
- Therefore, the correct options are:
- (i) Base-emitter junction is forward-biased.
- (iv) Base-collector junction is reverse-biased.

### Final Answer:
The correct options are (i) and (iv).

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