7. Waves, Energy & Reading Science Data

A wave is a disturbance that carries energy from place to place — usually without carrying the matter along with it. Sound, light, and ripples on water are all waves.

The parts of a wave:

• Crest — the highest point; trough — the lowest point.
• Wavelength — the distance from one crest to the next.
• Amplitude — the height from the rest line to a crest; bigger amplitude means more energy (a louder sound, a brighter light).
• Frequency — how many waves pass each second, measured in hertz (Hz).

Two main kinds: transverse waves move up-and-down across the direction of travel (light, water ripples); longitudinal waves squeeze and stretch along the direction of travel (sound). Sound needs a medium (air, water, solid) to travel through; light can travel through empty space.

The GED® Science test is as much about reasoning with data as memorizing facts. For any graph or table: read the title, axis labels, and units first; find the trend; and use only what the data shows — correlation is not causation.

⚠️ Common misconception: a wave does not carry the water (or air) along with it. The matter mostly bobs in place; only the energy moves forward.

💡 Tip: amplitude = energy/loudness/brightness; wavelength and frequency describe the wave's size and pace.