For a Common-Emitter amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 2 V. Suppose the current amplification factor of the transistor is 100. The base resistance is 1 kΩ. The input signal voltage will be:

0.01 V

$ R_C = 2k\Omega$

$V_0 = 2V$

$\alpha = 100 , R_B = 1K\Omega , V_i = ?$

Voltage Gain $ A  = \beta \frac{R_C}{R_B} = 100 \times \frac{2000}{1000} = 200 = \frac{V_o}{V_i}$

$\Rightarrow V_i = \frac{V_o}{200} = \frac{2}{200} = 0.01V$