In a normal operation of a transistor,

Options

A. the base-emitter junction is forward-biased
B. the base-collector junction is forward-biased
C. the base-emitter junction is reverse-biased
D. the base-collector junction is reverse-biased.

Answer

To solve the question regarding the normal operation of a transistor, we need to analyze the configuration and biasing of the transistor's junctions. Here's a step-by-step breakdown of the solution:

### Step 1: Identify the Type of Transistor
Transistors can be of two types: NPN or PNP. In this case, we are considering an NPN transistor, which consists of two n-type semiconductors and one p-type semiconductor.

### Step 2: Understand the Junctions
In an NPN transistor, there are three regions:
- Emitter (n-type)
- Base (p-type)
- Collector (n-type)

### Step 3: Determine the Biasing of the Junctions
For the transistor to operate normally:
- The **Base-Emitter (BE) junction** must be forward-biased.
- The **Base-Collector (BC) junction** must be reverse-biased.

### Step 4: Analyze the Connections
1. **Base-Emitter Junction**:
- The emitter (n-type) is connected to the negative terminal of the battery, and the base (p-type) is connected to the positive terminal. This configuration allows current to flow from the emitter to the base, indicating that the BE junction is forward-biased.

2. **Base-Collector Junction**:
- The collector (n-type) is connected to the positive terminal of the battery, while the base (p-type) is connected to the negative terminal. This configuration prevents current from flowing from the base to the collector, indicating that the BC junction is reverse-biased.

### Step 5: Evaluate the Options
Now, we can evaluate the provided options based on our analysis:
1. **Base-Emitter Junction is Forward Biased**: **Correct** (This is true as explained above).
2. **Base-Collector Junction is Forward Biased**: **Incorrect** (This is false as the BC junction is reverse-biased).
3. **Base-Emitter Junction is Reverse Biased**: **Incorrect** (This is false as the BE junction is forward-biased).
4. **Base-Collector Junction is Reverse Biased**: **Correct** (This is true as explained above).

### Conclusion
The correct options are:
- **1st Option**: Base-Emitter Junction is Forward Biased (Correct)
- **4th Option**: Base-Collector Junction is Reverse Biased (Correct)

The incorrect options are:
- **2nd Option**: Base-Collector Junction is Forward Biased (Incorrect)
- **3rd Option**: Base-Emitter Junction is Reverse Biased (Incorrect)