Which of the following statements is NOT correct regarding the travel of sound waves?
- (a)Sound waves can travel through water
- (b)Sound waves can travel through air
- (c)Sound waves can travel through steel
- (d)Sound waves can travel through vacuum
Answer
Why
Correct — D, the statement 'sound waves can travel through vacuum' is NOT correct. Sound is a mechanical (longitudinal) wave that needs a material medium — solid, liquid or gas — whose particles vibrate to pass the disturbance along. A vacuum has no particles, so sound cannot travel through it. Sound does travel through water, air and steel (fastest in solids such as steel).
Why the others are wrong
- (a)Sound waves can travel through water — This statement is true — sound travels well through water, indeed faster than through air — so it is not the incorrect one.
- (b)Sound waves can travel through air — This statement is true — air is the everyday medium for sound — so it is not the incorrect one.
- (c)Sound waves can travel through steel — This statement is true — sound travels fastest through solids such as steel — so it is not the incorrect one.
Concept
Sound is a mechanical longitudinal wave that requires a medium. Its speed rises from gases to liquids to solids (roughly 340 m/s in air, about 1500 m/s in water and around 5000 m/s in steel). Because a vacuum contains no particles to vibrate, no sound can pass through it — as shown by the classic bell-jar experiment.
The question asks for the FALSE statement, so pick the physically impossible case — travel through a vacuum — rather than any of the three true statements.
Key facts
- Sound is a mechanical wave and needs a material medium to travel.
- It cannot travel through a vacuum.
- It travels fastest in solids, slower in liquids and slowest in gases.
- Light and other electromagnetic waves, unlike sound, can travel through a vacuum.
Study next
Common traps
- Confusing sound with light — light needs no medium, sound does.
- Assuming a vacuum can carry sound just as air does.
Asked by presenting statements about sound travelling through media and asking which is correct or incorrect, hinging on the need for a medium.
Related PYQs
Which one of the following does not apply to sound waves in fluids ?
- (a) They transport energy
- (b) They need a medium to travel
- (c) They are transverse
- (d) They travel faster in liquids than in gases
Answer(c) They are transverse
Same properties-of-sound concept — sound needs a medium (so it cannot cross a vacuum) and is longitudinal, not transverse; option b there ('they need a medium') is exactly why sound fails in a vacuum here.
Practice
- practice — not a real PYQ
Sound travels fastest in
- (a)air
- (b)water
- (c)steel
- (d)vacuum
Answer(c) steel — sound is fastest in solids. - practice — not a real PYQ
Which one of the following can travel through a vacuum?
- (a)Sound
- (b)Light
- (c)A water wave
- (d)A wave on a string
Answer(b) Light — an electromagnetic wave needing no medium.