Multiple choice

What should be the approximate minimum distance between the source and the reflector in air so that an echo is heard?

  1. 34 m

  2. 17 m

  3. 10 m

  4. 68 m
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For an echo to be distinct, the reflected sound must reach the ear at least 0.1 second after the original sound. With sound speed at 344 m/s (at room temperature), the total distance traveled must be at least 34.4 meters, meaning the reflector should be at least 17.2 meters away.

Keep practicing — related questions