Sound · Class 9 · CBSE Science
Define the term 'echo' and state the minimum time gap required between the original sound and the reflected sound to hear a distinct echo in normal a…
Practice question from Sound (Class 9 · CBSE Science), with the correct answer and a step-by-step solution.
medium · Subjective · Q-7DC33C
Define the term 'echo' and state the minimum time gap required between the original sound and the reflected sound to hear a distinct echo in normal air.
Answer: An echo is a sound heard distinctly after being reflected from a rigid obstacle such as a cliff or a large wall. The minimum time gap required between the original sound and the reflected sound for the human ear to distinguish them as separate sounds is .
Solution
Persistence of hearing for the human ear is about . Consequently, the reflected sound must reach the ear after at least for an echo to be clearly heard.
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