In a common base transistor amplifier circuit,the input resistance in `100 Omega` and the output resistance is `10^5 Omega` What is the voltage amplification, when the emitter current is 5mA and current gain is 0.99?

Options

A. 991
B. 990
C. 890
D. 720

Explanation

To find the voltage amplification (Av) in a common base transistor amplifier circuit, we can use the following formula:

\[ A_V = \beta \times \frac{R_{out}}{R_{in}} \]

Where:
- \(A_V\) is the voltage amplification.
- \(\beta\) is the current gain.
- \(R_{out}\) is the output resistance.
- \(R_{in}\) is the input resistance.

Given:
- Input resistance, \(R_{in} = 100 \, \Omega\)
- Output resistance, \(R_{out} = 10^5 \, \Omega\)
- Current gain, \(\beta = 0.99\)

Now, let's substitute the values into the formula step by step:

1. **Calculate the ratio of output resistance to input resistance**:
\[ \frac{R_{out}}{R_{in}} = \frac{10^5 \, \Omega}{100 \, \Omega} = 10^3 \]

2. **Substitute the values into the voltage amplification formula**:
\[ A_V = \beta \times \frac{R_{out}}{R_{in}} = 0.99 \times 10^3 \]

3. **Calculate the voltage amplification**:
\[ A_V = 0.99 \times 1000 = 990 \]

Thus, the voltage amplification \(A_V\) is **990**.