MCQ
Two sound sources each emitting waves of wavelength $\lambda$ are fixed a given distance apart and an observer moves from one source to another with velocity $u$. Then number of beats heard by him per second is
- A$\frac{2 u}{\lambda}$
- B$\frac{u}{2 \lambda}$
- C$\frac{u}{\lambda}$
- D$\sqrt{u \lambda}$
