When a multimeter is connected to a transistor, it conducts when

Options

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

Answer

To determine when a multimeter conducts when connected to a transistor, we need to understand the basic operation of a transistor and the conditions for its functioning. Here’s a step-by-step solution:

### Step 1: Understand the Transistor Structure
A transistor has three terminals: the emitter (E), the base (B), and the collector (C). The behavior of the transistor depends on how these terminals are biased.

**Hint:** Remember the three terminals of a transistor and their roles: emitter, base, and collector.

### Step 2: Identify the Biasing Conditions
For a transistor to function properly:
- The base-emitter junction must be **forward biased**.
- The base-collector junction should be **reverse biased**.

**Hint:** Forward bias allows current to flow easily, while reverse bias restricts current flow.

### Step 3: Analyze the NPN Transistor
In an NPN transistor:
- The negative terminal of the power supply is connected to the emitter (E).
- The positive terminal is connected to the base (B).
- The collector (C) is typically connected to a higher voltage.

**Hint:** For an NPN transistor, remember that the emitter is usually connected to a lower potential than the base.

### Step 4: Check the Multimeter Connection
When using a multimeter to test the transistor:
- The multimeter will conduct when the base-emitter junction is forward biased. This means that the multimeter will show a reading when the base is at a higher potential than the emitter.

**Hint:** The multimeter measures current flow, which occurs when the base-emitter junction is forward biased.

### Step 5: Conclusion on Conductivity
If the base-emitter junction is forward biased, the transistor is "on," allowing current to flow through the multimeter. If the base-emitter junction is reverse biased, the transistor is "off," and the multimeter will not conduct.

**Hint:** Remember that for the multimeter to show a reading, there must be current flow, which only happens when the base-emitter junction is forward biased.

### Final Answer
The multimeter conducts when the **base-emitter junction is forward biased**.