Decibels quantify changes in signal strength due to attenuation or amplification by using what?

Decibels quantify changes in signal strength due to attenuation or amplification by using what?

• A. Logarithmic ratio
• B. Linear ratio
• C. Direct ratio
• D. Exponential ratio

Answer: (A)

Decibels quantify changes in signal strength using a logarithmic ratio. This means the level is derived from the ratio of two quantities (like power, or voltage/current for amplitude) with a logarithm. For power, the decibel value is 10 times the base-10 logarithm of the power ratio: dB = 10 log10(P2/P1). For voltage or current, it’s 20 times the base-10 logarithm of the amplitude ratio: dB = 20 log10(V2/V1). Using a logarithmic scale converts multiplicative changes into additive ones, which makes it easier to combine gains and losses. For example, doubling power is about +3.01 dB, while halving power is about -3.01 dB; doubling voltage corresponds to about +6.02 dB because power ∝ voltage squared. This is why a logarithmic ratio is used rather than a linear or exponential ratio.

Decibels quantify changes in signal strength using a logarithmic ratio. This means the level is derived from the ratio of two quantities (like power, or voltage/current for amplitude) with a logarithm. For power, the decibel value is 10 times the base-10 logarithm of the power ratio: dB = 10 log10(P2/P1). For voltage or current, it’s 20 times the base-10 logarithm of the amplitude ratio: dB = 20 log10(V2/V1). Using a logarithmic scale converts multiplicative changes into additive ones, which makes it easier to combine gains and losses. For example, doubling power is about +3.01 dB, while halving power is about -3.01 dB; doubling voltage corresponds to about +6.02 dB because power ∝ voltage squared. This is why a logarithmic ratio is used rather than a linear or exponential ratio.