Tag: waves

The loudness of sound is directly proportional to amplitude of sound wave. 

Unit for measuring the loudness of sound is decibel.
The intensity or loudness of a sound depends upon the extent to which the sounding body vibrates, i.e., the amplitude of vibration. A sound is louder as the amplitude of vibration is greater, and the intensity decreases as the distance from the source increases. Loudness is measured in units called decibels. 

Answer is B.

The intensity or loudness of a sound depends upon the extent to which the sounding body vibrates, i.e., the amplitude of vibration. A sound is louder as the amplitude of vibration is greater, and the intensity decreases as the distance from the source increases.
Sound levels is measured in units called decibels. 

If the amplitude of the sound is made 3 times its initial value, then its loudness will become nine times its initial value.
Loudness depends on the square of the amplitude of the wave. 
That is, $Loudness\propto { (Amplitude) }^{ 2 }$.
Thus, when amplitude of the wave is tripled, the loudness increases nine times.

Answer is C.

The intensity or loudness of a sound depends upon the extent to which the sounding body vibrates, i.e., the amplitude of vibration. A sound is louder as the amplitude of vibration is greater, and the intensity decreases as the distance from the source increases. Loudness or intensity of sound is measured in units called decibels. 

The loudness of sound is measured in units called decibels (dB). A decibel unit expresses the relative intensity of sounds on a scale from zero for the average least perceptible sound to about 100 dB, which is near the level most people find uncomfortably loud.

In S. I. unit of intensity of sound is
joule s$^{-1}$ m$^{-2}$ or watt m$^{-2}$
Intensity = sound energy/time $\times$ area

Intensity (or loudness) of sound         $L =10 \log _{10} \dfrac{I}{I _o}$

Decibel levels help us to understand the loudness of a sound with respect to a reference level. A decibel level of zero dB represents the lowest level of sound and a level of 80 dB represents the level of pain for humans.