Question

Unit of amplification factor of transistor is

• A. volt
• B. ampere
• C. ohm
• D. no unit

Hint:

Whenever you see a term like "factor," "coefficient," "ratio," or "index" (e.g., refractive index, efficiency, mechanical advantage) in physics, it is very likely to be a dimensionless quantity with no units.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The amplification factor of a transistor is a measure of how much it amplifies current or voltage. It is defined as a ratio of an output quantity to an input quantity.
Step 2: Detailed Explanation:
There are several amplification factors for a transistor, for example:
- Current amplification factor (\(\beta\)): In a common-emitter configuration, it is the ratio of the change in collector current (\(\Delta I_C\)) to the change in base current (\(\Delta I_B\)). \[ \beta = \frac{\Delta I_C}{\Delta I_B} \] Since this is a ratio of two currents (Ampere/Ampere), the units cancel out.
- Voltage amplification factor (\(A_v\)): This is the ratio of output voltage (\(V_{out}\)) to input voltage (\(V_{in}\)). \[ A_v = \frac{V_{out}}{V_{in}} \] This is a ratio of two voltages (Volt/Volt), so the units also cancel out.
In all cases, an amplification factor is a ratio of two quantities with the same units.
Step 3: Final Answer:
Since the amplification factor is a pure ratio, it is a dimensionless quantity and has no unit. Therefore, option (D) is correct.