T5B10 - Which decibel value most closely represents a power decrease from 12 watts to 3 watts?

Question

Which decibel value most closely represents a power decrease from 12 watts to 3 watts?

Answer Options

  • A) -1 dB
  • B) -3 dB
  • C) -6 dB
  • D) -9 dB

Correct Answer: C


Explanation

This problem requires calculating a ratio equivalent to multiple 3\text{ dB} power changes. Remember that a -3\text{ dB} change halves the power.

We start at 12\text{ W}: 12\text{ W} halved is 6\text{ W} (which is -3\text{ dB}). That 6\text{ W} halved again is 3\text{ W} (which is another -3\text{ dB}). Adding the two changes gives a total of -3\text{ dB} + -3\text{ dB} = -6\text{ dB}. Therefore, a power decrease from 12\text{ watts} to 3\text{ watts} represents a -6\text{ dB} change.


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