99 Percentile Qs Bank for JEE MainPhysicsWaves and Sound
On getting reflected at a surface, the intensity of sound is found to be decreased by (20 % ). If (A ) be the amplitude of the incident sound waves, then the amplitude of reflected sound waves is
Options
- A( 4 5 ~A )
- B( 2 5 A )
- C( 2 5 A )
- D( 1 5 A )
Correct answer
B. ( 2 5 A )
Step-by-step solution
Intensity of sound wave is directly proportional to the amplitude (A). ( aligned & i.e., I A^2 & ( I_ incident I_ reflected )= ( A_ incident A _ reflected )^2 (i) & I_ incident =I & I_ reflected =I-20 % of I &=I- I 5 = 4 5 I & A_ incident =A aligned ) ( ) From Eq. (i), we have ( aligned & I 4 I 5 = A^2 (A_ reflected )^2 & A_ rellected = 4 5 A^2 = 2 5 A aligned )