JAMB - Physics (2003 - No. 20)
If the distance from a point source of sound is doubled, by what factor does the intensity decrease?
4.00
2.00
0.50
0.25
解释
In general intensity of a wave is the rate of flow of energy across unit area normal to the direction of propagation of the wave intensity α1/r2 where r is the distance away from the point source. Thus if the distance from the point source of the sound wave is doubled, then the intensity will be decreased by a factor of 4