MCQ
Two loudspeakers $L$ and $L$ driven by a common oscillator and amplifier, are arranged as shown. The frequency of the oscillator is gradually increased from zero and the detector at $D$ records a series of maxima and minima. If the speed of sound is $330 \mathrm{~ms}$ then the frequency at which the first maximum is observed is


- A$165 \mathrm{~Hz}$
- ✓$330 \mathrm{~Hz}$
- C$496 \mathrm{~Hz}$
- D$660 \mathrm{~Hz}$