gen-define-sound-reflection-and-echo-and-give-one-short-worked-e-fd81

Define sound reflection and echo and give one short worked example.

# Sound Reflection and Echo ## **Sound Reflection** Sound reflection occurs when sound waves strike a surface and bounce back into the medium from which they came, following the law of reflection (angle of incidence = angle of reflection). ## **Echo** An echo is a specific case of sound reflection where the reflected sound is heard as a distinct repetition of the original sound. For an echo to be perceived separately, the reflected sound must reach the listener at least **0.1 seconds** after the original sound (due to the persistence of sound in the human ear). --- ## **Worked Example** **Problem:** A person shouts toward a cliff and hears an echo after 2 seconds. How far away is the cliff? (Speed of sound in air = 340 m/s) **Solution:** Given: - Time for echo = 2 s - Speed of sound (v) = 340 m/s The sound travels to the cliff and back, so: - Total distance = v × t = 340 × 2 = 680 m - Distance to cliff = 680 ÷ 2 = **340 m** **Answer:** The cliff is 340 meters away. --- *Key point: Remember to divide by 2 because the sound makes a round trip!*