MCAT Question A Day - 1/2/14 - Answer!
A stereo receiver has a power output of 50 W at a frequency of 1000 Hz. If the frequency is decreased to 100 Hz, the output decreases by 10 dB. What is the power output at 10 Hz?
A. 5.0 W
B. 10 W
C. 50 W
D. 100 W
The correct answer is (A). Choices (C) and (D) can be eliminated immediately. You must have less power than at 1000 Hz in order to get the decrease in sound level. The intensity is directly proportional to the power. A 10-dB drop is a drop of one order of magnitude. Decreasing 50 W by an order of magnitude gives 5 W.
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