In a sound wave, regions of the medium alternate between ______ and _______.

In a sound wave, regions of the medium alternate between ______ and _______.

• A. compressed and rarefied
• B. dense and light
• C. fast and slow
• D. solid and gas

Answer: (A)

Sound travels as a longitudinal wave, so the particles of the medium move mainly in the same direction as the wave. This motion creates repeating zones of higher pressure and density where particles are pressed together (compression) and zones of lower pressure and density where they spread apart (rarefaction). As the wave passes, these compressions and rarefactions move through the medium, carrying energy with them. The other ideas don’t describe these alternating regions: density differences without the repeating pattern, or terms about speed, or states of matter.

Sound travels as a longitudinal wave, so the particles of the medium move mainly in the same direction as the wave. This motion creates repeating zones of higher pressure and density where particles are pressed together (compression) and zones of lower pressure and density where they spread apart (rarefaction). As the wave passes, these compressions and rarefactions move through the medium, carrying energy with them. The other ideas don’t describe these alternating regions: density differences without the repeating pattern, or terms about speed, or states of matter.