6 (a.a.) Longitudinal and Transverse Waves
There are two types of mechanical waves: transverse waves and longitudinal waves.
If you stretch out a spring toy and push and pull one end, you can produce a longitudinal wave. Longitudinal waves (lawn juh too duh nul) move the medium parallel to the direction in which the waves travel. The coils in the spring move back and forth parallel to the wave motion. In some parts of the spring, the coils are close together. In other parts of the spring, the coils are more spread out. The parts where the coils are close together are called compressions (kum presh unz). The parts where the coils are spread out, or rarified, are called rarefactions (rair uh fak shunz) .
As compressions and rarefactions travel along the spring toy, each coil moves forward and then back. The energy travels from one end of the spring to the other, creating a wave. After the wave passes, each coil returns to the position where it started.
As compressions and rarefactions travel along the spring toy, each coil moves forward and then back. The energy travels from one end of the spring to the other, creating a wave. After the wave passes, each coil returns to the position where it started.
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Sound is also a longitudinal wave. In air, sound waves cause air particles to move back and forth. In areas where the particles are pushed together, compressions form. In between the compressions, particles are spread out. These are rarefactions.
Transverse Waves
When you make a wave on a rope, the wave moves from one end of the rope to the other. But the rope itself moves up and down or from side to side, at right angles to the direction in which the wave travels. Waves that move the medium at right angles to the direction in which the waves travel are called transverse waves. Transverse means “across.” As a transverse wave moves, the particles of the medium move across, or at a right angle to, the direction of the wave.
The high part of a transverse wave is called a crest, and the low part is called a trough (trawf).
When you make a wave on a rope, the wave moves from one end of the rope to the other. But the rope itself moves up and down or from side to side, at right angles to the direction in which the wave travels. Waves that move the medium at right angles to the direction in which the waves travel are called transverse waves. Transverse means “across.” As a transverse wave moves, the particles of the medium move across, or at a right angle to, the direction of the wave.
The high part of a transverse wave is called a crest, and the low part is called a trough (trawf).
