A power amplifier gives an output power of 1 W for an input of 100 mW. Its power gain expressed in dB is:

Correct option is C

​$$\textbf{Solution:} \\\text{The power gain (in decibels, dB) is calculated using the formula:} \\\\\text{Power Gain (dB)} = 10 \cdot \log_{10} \left( \frac{P_\text{out}}{P_\text{in}} \right) \\\\\text{Where:} \\\begin{aligned}&\bullet \quad P_\text{out} = 1\, \text{W (output power).} \\&\bullet \quad P_\text{in} = 100\, \text{mW} = 0.1\, \text{W (input power).}\end{aligned} \\\\\text{Step 1: Substitute the values:} \\\text{Power Gain (dB)} = 10 \cdot \log_{10} \left( \frac{1}{0.1} \right) \\\text{Power Gain (dB)} = 10 \cdot \log_{10}(10) \\\\\text{Step 2: Simplify:} \\\log_{10}(10) = 1 \\\\\text{Power Gain (dB)} = 10 \cdot 1 = 10\, \text{dB}$$​​