Q) What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts?

A) 6 dB

The following formula will allow you calculate the ratio in decibels given two different power values.

dB = 10 * Log(Pa / Pb)

Using the figures in the question:

dB = 10 * Log (12 / 3)

dB = 10 * Log(4)

dB = 10 * 0.6

dB = 6

This question is from the FCC Element 2 Technician Class Question Pool

Effective July 1, 2010 for examinations and is valid until June 30, 2014

A) 6 dB

**NJ2X Notes**:The following formula will allow you calculate the ratio in decibels given two different power values.

dB = 10 * Log(Pa / Pb)

Using the figures in the question:

dB = 10 * Log (12 / 3)

dB = 10 * Log(4)

dB = 10 * 0.6

dB = 6

This question is from the FCC Element 2 Technician Class Question Pool

Effective July 1, 2010 for examinations and is valid until June 30, 2014