Decibel
Coulomb
Hum
Cycles
Answer is Wrong!
Answer is Right!
The correct answer is A. Decibel.
A decibel (dB) is a logarithmic unit that expresses the ratio of a physical quantity (such as sound pressure) to a reference value. The reference value for sound pressure is 20 micropascals (μPa), which is the threshold of human hearing. A sound pressure of 120 dB is 100 times louder than a sound pressure of 20 dB.
B. Coulomb is the unit of electric charge.
C. Hum is a low-pitched sound that is often heard in electrical appliances.
D. Cycles is the unit of frequency.