A working transitor with its three legs marked `P, Q and R` is tested using a multimeter No conduction is found between `P, Q `by connecting the common (negative) terminal of the multimeter to `R`and the other (positive) terminal to or `Q` some resistance is seen on the multimeter . Which of the following is true for the transistor ?

Options

A. It is an n - p - n transistor with R as base
B. It is an p - n - p transistor with R as collector
C. It is an p - n - p transistor with R as emitter
D. It is an n - p - n transistor with R as collector

Answer

To solve the problem, we need to analyze the behavior of the transistor based on the information provided about the multimeter test results.

### Step-by-Step Solution:

1. **Understanding the Transistor Configuration**:
- A transistor has three terminals: emitter (E), base (B), and collector (C).
- In an NPN transistor, the emitter and collector are n-type semiconductors, while the base is a p-type semiconductor.
- In a PNP transistor, the emitter and collector are p-type semiconductors, while the base is an n-type semiconductor.

2. **Analyzing the Test Results**:
- The problem states that no conduction is found between terminals P and Q when the common negative terminal of the multimeter is connected to R.
- This indicates that P and Q must be of the same type of semiconductor (either both n-type or both p-type).

3. **Identifying the Base**:
- Since R is connected to the negative terminal and shows some resistance when the positive terminal is connected to either P or Q, it implies that R is a p-type semiconductor.
- Consequently, P and Q must be n-type semiconductors.

4. **Determining the Type of Transistor**:
- Given that R is a p-type semiconductor and both P and Q are n-type semiconductors, we can conclude that the transistor is an NPN type.
- In an NPN transistor, the base (R) is p-type, while the collector (P) and emitter (Q) are n-type.

5. **Conclusion**:
- Therefore, the correct statement about the transistor is that it is an NPN transistor with R as the base.

### Final Answer:
The transistor is an NPN transistor with R as the base.