In a stationary wave that forms as a result of reflection of wave from an obstacle, the ratio of this amplitude at an antinode to the amplitude at node is n. The fraction of energy reflected is

Options

A. `[(x-1)/x]^2`
B. `[x/(x+1)]^2`
C. `[(x-1)/(x+1)]^2`
D. `[1/x]^2`

Answer

C

Explanation

`(A_1+A_2)/(A_1-A_2)=x,A_2/A_1=(x-1)/(x+1),` Energy `prop A^2`
`=implies ((x-1)/(x+))^2`