What is amplitude?

• A. The relationship between two signals that share the same frequency
• B. The number of cycles per second
• C. The physical length of one complete cycle
• D. The size or signal strength of a waveform

Answer: (D)

Amplitude is the size or strength of a waveform—the maximum amount the signal swings from its baseline. In practical terms, for an electrical or audio signal, it’s the peak value (for example, volts or amperes) the waveform reaches. Sometimes we talk about peak-to-peak amplitude (twice the peak value) or RMS amplitude, which relates to the power the signal can deliver.

This concept is distinct from how often the wave repeats (frequency) or how long one cycle lasts (period). Frequency tells you the number of cycles per second, while amplitude tells you how large the swings are. In other words, a high-amplitude signal is a strong, loud, or powerful signal, independent of how fast it oscillates.