GED Science TestPhysical ScienceMedium
A technician is setting up an experiment to demonstrate how sound travels. They place a ringing alarm clock inside a sealed glass jar and then begin to pump the air out of the jar. As the air is removed, the sound of the alarm clock becomes fainter and fainter until it is almost inaudible. This experiment best demonstrates that sound waves are:
- AElectromagnetic waves that travel at the speed of light.
- BLongitudinal waves that require a medium to travel.
- CStanding waves that are amplified by enclosed spaces.
- DTransverse waves that can travel through a vacuum.
Show answer & explanationAnswer & explanation
Correct answer: B. Longitudinal waves that require a medium to travel.
Sound waves are mechanical waves, specifically longitudinal waves, which means they require a medium (like air, water, or solids) to propagate. Removing the air (a medium) from the jar causes the sound to diminish because there are fewer particles to transmit the vibrations.
Why the other options are wrong
- A. Electromagnetic waves (like light) do not require a medium and can travel through a vacuum, which contradicts the observation.
- C. While sound can form standing waves and be amplified, this experiment specifically focuses on the necessity of a medium, not wave amplification or type of standing wave.
- D. Transverse waves have oscillations perpendicular to propagation; sound is longitudinal. Sound also cannot travel through a vacuum.
Sound Waves
Mechanical, longitudinal waves that propagate through a medium by means of particle displacement.
- Require a medium (solid, liquid, gas) to travel.
- Are longitudinal waves: particles oscillate parallel to wave direction.
- Cannot travel through a vacuum.
- Speed depends on the properties of the medium.
Memory trick: Sound needs Stuff, Light Loves Space.