For a transistor , the correct statement is

Options

A. Collector current increases with increase in emitter current
B. Collector current decreases with increase in emitter current
C. Collector current increases with decrease in emitter current
D. Collector current decreases with decrease in emitter current

Answer

To solve the question regarding the correct statements about a transistor, we will analyze the relationships between the collector current (Ic) and the emitter current (Ie) based on the characteristics of a transistor, particularly focusing on an NPN transistor.

### Step-by-Step Solution:

1. **Understanding Transistor Current Relationships**:
- For an NPN transistor, the relationship between the collector current (Ic) and the emitter current (Ie) is given by the equation:
\[ I_c = \alpha I_e \]
where \(\alpha\) is the common base current gain (a value between 0 and 1).

2. **Analyzing Statement A**:
- Statement A claims that "collector current increases with increase in emitter current."
- From the equation \(I_c = \alpha I_e\), if \(I_e\) increases, \(I_c\) also increases since \(\alpha\) is a constant.
- **Conclusion**: Statement A is **true**.

3. **Analyzing Statement B**:
- Statement B claims that "collector current decreases with increase in emitter current."
- This statement contradicts the direct relationship established in the previous step. If \(I_e\) increases, \(I_c\) cannot decrease.
- **Conclusion**: Statement B is **false**.

4. **Analyzing Statement C**:
- Statement C claims that "collector current increases with decrease in emitter current."
- This statement also contradicts the established relationship. If \(I_e\) decreases, \(I_c\) will also decrease.
- **Conclusion**: Statement C is **false**.

5. **Analyzing Statement D**:
- Statement D claims that "collector current decreases with decrease in emitter current."
- According to the relationship \(I_c = \alpha I_e\), if \(I_e\) decreases, \(I_c\) will also decrease.
- **Conclusion**: Statement D is **true**.

### Final Conclusion:
From the analysis, we find that:
- **Statement A is true**.
- **Statement B is false**.
- **Statement C is false**.
- **Statement D is true**.

Thus, the correct statements regarding the transistor are **A and D**.