A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2 m and 3 m respectively from the source. The ratio of the intensities of the waves at P and Q is ......

A point source emits sound equally in all directions in a non-absorbin

1.	A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2 m and 3 m respectively from the source. The ratio of the intensities of the waves at P and Q is ......
Answer» <P>`3:2` `2:3` `9:4` `4:9` SOLUTION :We have,`I = (P)/(A) = (P)/( A pi R ^(2)) IMPLIES I prop (1)/(r ^(2))` `therefore (I _(1))/( I _(2)) = (r _(2) ^(2))/( r _(1) ^(2)) = ((3) ^(2))/( (2) ^(2)) = 9/4` `therefore I _(1) :I _(2) =9:4`