26 Introduction to Circuits and DC Instruments

Electric circuits form the foundation of modern technology. They are responsible for controlling how electrical energy is transferred, transformed, and used in devices ranging from simple household tools to advanced medical and computational systems.

Electric circuits are commonplace. Some are simple, such as those in flashlights. Others, such as those used in supercomputers, are extremely complex. Regardless of their complexity, all circuits are governed by the same fundamental physical principles.

This collection of modules takes the topic of electric circuits a step beyond simple circuits. When a circuit is purely resistive, the relationships developed in earlier chapters apply directly to both direct current (DC) and alternating current (AC) systems. However, matters become more complex when additional circuit elements, such as capacitors, are introduced.

In this chapter, we consider what happens when capacitors are connected to DC voltage sources, building a foundation for understanding more advanced circuit behavior. The interaction of capacitors and other nonresistive devices with AC will be explored in a later chapter.

Finally, a number of important DC instruments, such as meters that measure voltage and current, are covered in this chapter. These measurement tools are essential for analyzing circuits and are widely used in both engineering and healthcare settings.