NCERT Solutions for Class 9th Science Chapter 10 .4 Energy of Sound Waves — Pause and Ponder

Book page 19210 Updated on2026-09-08

Q1.
When sound travels from a tuning fork to your ear, which of the following actually reaches your ear? (i) Air particles near the tuning fork (ii) Energy carried by sound waves (iii) The tuning fork material (iv) A continuous stream of compressed air
Answer

(ii) Energy carried by sound waves.

The air particles that were beside the prongs stay beside the prongs. Each one merely oscillates about its mean position and nudges its neighbour; the neighbour nudges the next, and so on. What travels the whole way from the fork to your eardrum is the disturbance, and with it the energy.

OptionVerdictWhy
(i) Air particles near the tuning forkWrongThose particles only vibrate about their mean positions; they never make the journey
(ii) Energy carried by sound wavesCorrectEnergy is transferred from particle to particle by collisions
(iii) The tuning fork materialWrongThe steel stays in your hand; nothing leaves it
(iv) A continuous stream of compressed airWrongCompressions and rarefactions alternate; there is no one-way flow of air
Tip: a microphone makes this concrete. Sound energy arriving at its diaphragm is converted into electrical energy; a speaker runs the same chain backwards. Energy is the thing being passed around at every stage.
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