The sound from two loudspeakers is received by a microphone at a point far away along the line through the speakers.The microphone registers maximum intensity when the speakers are 20 cm apart.The sound intensity decreases as the distance between the speakers is increased,reaching zero at a separation of 91 cm.If the distance between the speakers continues to increase,at what separation will the sound intensity again be a maximum?
A)162 cm
B)172 cm
C)182 cm
D)192 cm

Question

Quizplus · Accepted Answer

The sound intensity is maximum when the path difference between the waves from the two speakers is a multiple of the wavelength. The first maximum occurs at 20 cm, and the first minimum at 91 cm, indicating a half-wavelength difference of 71 cm. The next maximum will occur at a full wavelength difference of 142 cm (71 cm x 2) from the initial maximum, so 20 cm + 142 cm = 162 cm.

The Sound from Two Loudspeakers Is Received by a Microphone