Attenuation is measured in and reported as what kind of change?

• A. Decibels; Relative change
• B. Watts; Relative change
• C. Hertz; Relative change
• D. Decibels; Absolute change

Answer: (A)

Attenuation describes how much a signal’s strength decreases as it travels through a medium. It is measured in decibels because dB express a ratio, which is perfect for describing how the output compares to the input. Because attenuation is about the change relative to the original level, it is a relative change, not an absolute amount. In practice you can calculate it as 10 log10(Pout/Pin) for power, or 20 log10(Vout/Vin) for amplitude, and you add these losses across components. The other options don’t fit: watts would be an absolute power value, hertz would measure frequency, and an absolute change wouldn’t convey the comparison to the starting level.