To hear a clear echo, the reflecting surface should be at least how much away from the source of sound?
واضح بازگشت سننے کے لئے ، عکاسی کرنے والی سطح کم از کم آواز کے منبع سے کتنا دور ہونی چاہئے؟
Answer: 17 metre
Explanation
To hear a distinct echo, the reflecting surface must be at least 17 meters away from the sound source.
This distance allows the sound to travel to the surface and back (total 34 meters) in 0.1 seconds, the minimum time gap for the human ear to perceive an echo.
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