What change in transmitter power results in a 3 dB decrease?

The decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, such as power. A fundamental rule of thumb in radio electronics is that a 3 dB change corresponds exactly to a factor of 2 in power. Therefore, a 3 dB increase means doubling the power, and a 3 dB decrease means halving the power (dividing the original power by 2). The other options represent different ratios; for example, dividing by 4 would correspond to a 6 dB decrease, and dividing by 10 would be a 10 dB decrease.