In an experiment of CE configuration of $$n-p-n$$ transistor, the transfer characteristics are observed as given in figure. If the input resistance is $$200\Omega$$ and output resistance is $$60\Omega$$, the voltage gain in this experiment will be ______.

$$\Delta I_C = 15 - 5 = 10\ \text{mA} = 10 \times 10^{-3}\ \text{A}$$

$$\Delta I_B = 300 - 100 = 200\ \mu\text{A} = 200 \times 10^{-6}\ \text{A}$$

Current gain, $$\beta = \frac{\Delta I_C}{\Delta I_B} = \frac{10 \times 10^{-3}}{200 \times 10^{-6}} = \frac{10}{200} \times 10^3 = 50$$ 

Voltage gain, $$A_v = \beta \left( \frac{R_{\text{out}}}{R_{\text{in}}} \right)$$ 

$$\implies A_v = 50 \times \left( \frac{60}{200} \right) = \frac{3000}{200} = 15$$