What is the difference between a longitudinal wave and a transverse wave? Give an example.

• A. Longitudinal waves vibrate perpendicular to the direction of travel; transverse vibrate parallel.
• B. Both wave types have the same orientation.
• C. Longitudinal waves vibrate parallel to the direction of travel (sound); transverse waves vibrate perpendicular (light).
• D. Only transverse waves can travel through air.

Answer: (C)

The main idea is how the particles move in the medium as the wave passes. In a longitudinal wave, the particles vibrate along the same line as the wave travels, causing regions of compression and rarefaction. Sound in air is a classic example: the air molecules oscillate back and forth in the direction the wave moves, while the sound energy propagates forward. In a transverse wave, the particles move perpendicular to the direction of travel, creating crests and troughs; light is the familiar example where electric and magnetic fields oscillate at right angles to the direction the wave moves. So the correct description is that longitudinal waves vibrate parallel to the direction of travel (like sound), while transverse waves vibrate perpendicular (like light). The other statements mix up the directions or claim only transverse waves can travel through air, which isn’t true since sound (a longitudinal wave) travels through air.