Which of the following is normally a low voltage DC power source?

A battery is typically a low voltage DC power source because it stores electrical energy chemically and releases it as direct current (DC) electricity. In many applications, batteries operate at relatively low voltages, often ranging from 1.2 volts for single cells to around 12 volts or higher for battery packs. This characteristic makes batteries versatile and widely used in various devices and systems that require DC power.

Transformers, on the other hand, are used to convert AC voltages to different levels but do not generate DC power. Capacitors store electrical energy and can release it quickly, but they do not serve as a continuous power source in the same way that batteries do. Alternators generate alternating current (AC) power and are typically used in systems that need AC electricity rather than low voltage DC sources. Therefore, choosing batteries is the correct response, as they are specifically designed to provide low voltage DC power.