Check sibling questions
Class 9
Chapter 12 Class 9 - Sound (Deleted)

When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?


As the temperature increases, the speed of the sound also increases.

Hence, the speed of sound on a hotter day is more.


We know that, echo occurs when time difference between original sound and reflected sound is atleast 0.1 second.



Speed = Distance / Time

Time = Distance / Speed


Therefore, for same distance, if speed is higher,

time taken would be less.



If the time would be less than 0.1 second, then the echo won’t be heard.

If the time would be more than or equal to 0.1 second, then the echo can be heard.

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CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Accounts and English at Teachoo