What is a sine wave and where would you encounter it in mechatronics?

• A. A smooth periodic waveform; encountered in AC power, motor feedback signals, and sinusoidal sensors.
• B. A square wave used for PWM
• C. A random noise signal
• D. A DC signal with constant voltage

Answer: (A)

A sine wave is a smooth, repeating oscillation with a constant amplitude and period. In practice, it’s the pure, single-frequency signal described by a sine function.

You’ll encounter it in mechatronics in several common places. AC power systems deliver voltage and current that vary sinusoidally, so motors are typically powered by a sine-shaped supply. Motor feedback often involves sinusoidal signals, such as back-EMF in brushless motors or outputs from resolvers that provide sine (and cosine) waveforms to determine precise position and speed. Many sensors, like LVDTs and sine-cosine encoders, produce sinusoidal voltages to translate physical displacement into electrical signals.

This makes the sine wave a foundational concept because it represents a clean, well-understood waveform used for driving, measuring, and analyzing dynamic systems. Other options describe different signal types—square waves for PWM, random noise, or a constant DC level—so they don’t fit the typical, smooth periodic nature of a sine wave.