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Welcome to our Physics lesson on Echo, this is the fourth lesson of our suite of physics lessons covering the topic of Sound Waves. Intensity and Sound Level, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.
Echo is the phenomenon of sound reflection when it encounters a large obstacle. As a result, a listener can hear his voice twice: one when he produces the sound and the other when his voice turns back. This helps us calculate the distance from a cliff, a mountain, a building, etc. Let's consider an example.
A girl standing near a wall shouts and then she hears the echo of her voice after 3.2 s. Calculate the distance of the girl from the wall. Take the speed of sound in air equal to 343 m/s.
The distance travelled by the sound is twice the distance of the girl from the wall as the sound turns back at the girl's ear after hitting the wall. Also, the speed of sound is constant because sound moves within the same medium (air) during the entire process. Thus, we apply the formula of uniform motion to calculate the distance s of the girl from the wall, i.e.
Therefore, the distance s of the girl from the wall is
You have reached the end of Physics lesson 11.5.4 Echo. There are 7 lessons in this physics tutorial covering Sound Waves. Intensity and Sound Level, you can access all the lessons from this tutorial below.
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