Incident wave `y= A sin (ax + bt+ pi/2)` is reflected by an obstacle at x = 0 which reduces intensity of reflected wave by 36%. Due to superposition, the resulting wave consists of a standing wave and a travelling wave given by
`y= -1.6 sin ax sin bt + cA cos (bt + ax)`
where A, a, b and c are positive constants.
1. Amplitude of reflected wave is

Options

A. 0.6A
B. 0.8A
C. 0.4A
D. 0.2A

Answer

B

Explanation

Intensity of reflected wave =100-36=64%`implies`amplitude `(alpha(sqrt(I))` of reflected wave=0.8A