Question
Physics Question on Waves
Two sources are at a finite distance apart. They emit sound of wavelength λ . An observer situated between them on line joining the sources, approaches towards one source with speed u , then the number of beats heard per second by observer will be
A
λ2u
B
λu
C
2λu
D
uλ
Answer
λ2u
Explanation
Solution
n1=(vv+u)n and n2=(vv−u)n Number of beats per second x=n1−n2 =(vv+u)n−(vv−u)n =(vv+u−v+u)n =2u(vn)=v2u