The maximum displacement of the medium from the rest position.

• A. Energy
• B. Hertz
• C. Amplitude
• D. Frequency

Answer: (C)

The maximum displacement from the rest position is called the amplitude. When a wave moves through a medium, each particle oscillates around its equilibrium point, and the largest distance it moves from that resting position is the amplitude. You can picture a sine wave on a string: the height of the crest (or the depth of the trough) from the center line is the amplitude. Larger amplitudes mean the particles move farther from rest and, for waves, generally carry more energy, though energy and displacement aren’t the same thing. The other terms describe different properties: Hertz is a unit of frequency (how often the cycle repeats), and frequency is that rate of repetition. Energy is related to how much work the wave can do, and it increases with amplitude, but the specific maximum displacement is the amplitude.