what is an echo...?? tell me first tomorrow I have exam
Answers
An echo is the repetition of sound that results as a reflection from a surface. Multiple reflection of sound is the successive reflection of sound from various reflecting surfaces. We cannot hear an echo unless the reflecting surface is beyond a specified distance from the source of the sound. The sensation of sound persists for 0.1 second. The minimum distance required to hear an echo is 17.2 metres.
When a sound wave is incident on a solid or liquid surface, it bounces back onto the same medium. This is known as the reflection of sound. Like light, sound too undergoes reflection from any hard surface and obeys the same laws of reflection, which light obeys.
Laws of Reflection of Sound
The direction in which the sound wave is incident and the direction, in which it is reflected, make equal angles with the normal to the reflecting surface, at the point of incidence.
The incident sound wave, the reflected wave and the normal at the point of incidence are in the same plane.
