From the given transfer characteristic of a transistor in CE configuration, the value of power gain of this configuration is $$10^x$$, for $$R_B = 10$$ k$$\Omega$$, and $$R_C = 1$$ k$$\Omega$$. The value of $$x$$ is _____.

Using the transfer characteristic graph to evaluate AC current gain ($$\beta$$):

$$\beta = \frac{\Delta I_C}{\Delta I_B} = \frac{(50 - 10) \times 10^{-3}\text{ A}}{(500 - 100) \times 10^{-6}\text{ A}} = \frac{40 \times 10^{-3}}{400 \times 10^{-6}} = 100$$

Using the AC power gain formula for CE configuration: $$A_p = \beta^2 \left(\frac{R_C}{R_B}\right)$$

$$A_p = (100)^2 \times \left(\frac{1}{10}\right) = 10000 \times \frac{1}{10} = 1000 = 10^3$$

$$A_p = 10^x \implies 10^3 = 10^x \implies x = 3$$