A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it there is a building adjoining the park and on right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.

Question

TextEcho and Its FormationNCERT Exemplar

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What is an echo? Under what conditions can it be heard?

Explain how 'echo' is produced.

Frequency and Time Period of Sound Wave

Relationship Between Wavelength, Frequency and Speed

Speed of Sound in Different Media

Reflection of Sound Waves

Echo and Its Formation

What should be the minimum distance between the listener and the reflector to hear an echo of sound propagating with a speed v m s⁻¹?

Does the speed of sound increase or decrease on a hotter day? Justify.

Establish the relationship between speed of sound, its wavelength and frequency. If speed of sound in air is 340 m s⁻¹, calculate.

An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m s–1?