For a common emitter amplifier, the audio frequency voltage across the collector resistance `2kOmega` is 2V. If the current amplication factor of the transistor is 200, and the base resistance is `1.5 kOmega`, the input signal voltage and base current are

Options

A. `0.15V and 10muA`
B. `0.015V and 1A`
C. `0.0015 V and 1 mA`
D. `0.0075V and 5 muA`

Answer

To solve the problem step by step, we will follow the given information and use the relevant formulas for a common emitter amplifier.

### Step 1: Identify Given Values
- Collector resistance, \( R_C = 2 \, k\Omega = 2000 \, \Omega \)
- Output voltage across collector resistance, \( V_C = 2 \, V \)
- Current amplification factor (beta), \( \beta = 200 \)
- Base resistance, \( R_B = 1.5 \, k\Omega = 1500 \, \Omega \)

### Step 2: Calculate Collector Current \( I_C \)
Using Ohm's law, we can find the collector current \( I_C \):
\[ I_C = \frac{V_C}{R_C} = \frac{2 \, V}{2000 \, \Omega} = 0.001 \, A = 1 \, mA \]

### Step 3: Calculate Base Current \( I_B \)
The relationship between collector current and base current is given by:
\[ I_C = \beta \cdot I_B \implies I_B = \frac{I_C}{\beta} \]
Substituting the known values:
\[ I_B = \frac{1 \, mA}{200} = \frac{0.001 \, A}{200} = 0.000005 \, A = 5 \, \mu A \]

### Step 4: Calculate Input Voltage \( V_B \)
The input voltage across the base can be calculated using Ohm's law:
\[ V_B = I_B \cdot R_B \]
Substituting the values:
\[ V_B = 5 \, \mu A \cdot 1500 \, \Omega = 5 \times 10^{-6} \, A \cdot 1500 \, \Omega = 0.0075 \, V = 7.5 \, mV \]

### Summary of Results
- Input signal voltage \( V_B = 7.5 \, mV \)
- Base current \( I_B = 5 \, \mu A \)