Master the Airwaves with Ham Radio General Class 2025 – Transmit Success Today!

Question: 1 / 545

A two-times increase or decrease in power results in a change of how many dB?

Approximately 2 dB

Approximately 3 dB

When discussing power levels in decibels (dB), it's important to understand the logarithmic relationship between power and decibels. A change of 3 dB corresponds to a doubling or halving of power.

This is derived from the formula for decibels, which is:

\[ \text{dB} = 10 \log_{10} \left( \frac{P2}{P1} \right) \]

Where \( P2 \) is the new power and \( P1 \) is the original power. If you double the power (i.e., \( P2 = 2 \times P1 \)), you substitute into the formula to find the change:

\[ \text{dB} = 10 \log_{10} \left( \frac{2P1}{P1} \right) = 10 \log_{10} (2) \]

Calculating \( \log_{10} (2) \) gives approximately 0.301, hence:

\[ 10 \times 0.301 \approx 3.01 \text{ dB} \]

This rounding leads us to state that a 2-fold increase in power translates to an increase

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Approximately 6 dB

Approximately 12 dB

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