Question

The minimum distance between the source of the sound and the obstacle for an echo (at 20°C) to take place is:
(A) 17.2 m
(B) 1.72 m
(C) 17.8 m
(D) 34.4 m

Answer 1

Explanation:

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Answer 2

Dear Student,

◆ Answer -

(A) 17.2 m

● Explanation -

For hearing distunct echoes, minimum time between two sounds must be 0.1 s.

Time taken to hear echo is calculated by -

Time taken = 2 × distance between person and cliff / speed of sound

Distance between person and cliff = time taken × speed of sound / 2

For minimum time 0.1 s,

Distance between person and cliff = 0.1 × 344 / 2

Distance between person and cliff = 17.2 m

Therefore, The minimum distance between the source of the sound and the obstacle for an echo (at 20°C) to take place is 17.2 m.

Hope this helps you...