#### Two sources of sound placed close to each other are emitting progressive waves given by y1 = 4 sin 600 t and y2 = 5 sin 608 t. An observer located near these two sources of sound will hear: Option 1) 4 beats per second with intensity ratio 25: 16 between waxing and waning. Option 2) 8 beats per second with intensity ratio 25 : 16 between waxing and waning. Option 3) 8 beats per second with intensity ratio 81 : 1 between waxing and waning. Option 4) 4 beats per second with intensity ratio 81 : 1 between waxing and waning.

As we learnt in

Beat Frequency -

module of

- wherein

Where are frequency of two wave differ slightly  in value of frequency.

Ratio of maximum and minimum intensity -

-

....................(i)

....................(ii)

Correct option is 4.

Option 1)

4 beats per second with intensity ratio 25: 16 between waxing and waning.

Incorrect

Option 2)

8 beats per second with intensity ratio 25 : 16 between waxing and waning.

Incorrect

Option 3)

8 beats per second with intensity ratio 81 : 1 between waxing and waning.

Incorrect

Option 4)

4 beats per second with intensity ratio 81 : 1 between waxing and waning.

Correct