Amp Up Your Brainpower for 2025: Master the SQA Higher Physics Exam!

The primary function of a capacitor in electrical circuits is to store electrical energy. Capacitors are components that can accumulate and hold an electric charge. When connected to a power source, they can charge up, accumulating energy in the form of an electric field between their plates. This stored energy can then be released when needed, making capacitors essential for various applications in electrical and electronic circuits.

For instance, capacitors play a crucial role in smoothing voltage fluctuations in power supplies, serving as energy reservoirs during periods of high demand. They are also used in timing circuits, coupling signals between stages in amplifiers, and filtering applications, where they help to maintain stable voltages and improve signal integrity.

Other options may pertain to different functions related to circuit behavior but do not align with the primary function of a capacitor. Converting AC to DC is typically achieved using rectifiers, while increasing voltage levels is done by transformers. Measuring current flow is the role of devices like ammeters, not capacitors. Hence, the emphasis on the capacity to store electrical energy is what defines the primary function of capacitors in electrical circuits.