An echo is the phenomenon of repetition of sound of a source by reflection from an obstacle. Note: A distinct echo is heard only when the reflected sound reaches the ears after minimum 0 . 1 s of hearing the original sound.

Together with Science Class 9>Chapter 12 - Sound>ASSESS YOURSELF>Q 32

EASY

9th CBSE

IMPORTANT

Earn 100

Define loudness of sound.

Important Questions on Sound

MEDIUM

9th CBSE

IMPORTANT

Together with Science Class 9>Chapter 12 - Sound>ASSESS YOURSELF>Q 33

Explain how human ear works in the transmission of sound wave to the brain.

MEDIUM

9th CBSE

IMPORTANT

Together with Science Class 9>Chapter 12 - Sound>ASSESS YOURSELF>Q 34

When sound is reflected from a distant object, an echo is produced and heard in a winter night. Now, if the distance between the reflecting surface and the source of sound production remains the same, will you hear the echo of the same sound on a summer day? Explain.

MEDIUM

9th CBSE

IMPORTANT

Together with Science Class 9>Chapter 12 - Sound>ASSESS YOURSELF>Q 35

How are ultrasonic waves used for direction signalling?

MEDIUM

9th CBSE

IMPORTANT

Together with Science Class 9>Chapter 12 - Sound>ASSESS YOURSELF>Q 36

Draw a diagram to represent a sound wave.

EASY

9th CBSE