THE LEARNING GOALS FOR THIS CHAPTER ARE:
Understand the concepts of linearity and equivalence
Know how to analyze electric circuits using the principle of superposition
Be able to calculate a Thévenin equivalent circuit for a linear circuit
Be able to calculate a Norton equivalent circuit for a linear circuit
Understand when and how to use a source transformation
Be able to use the maximum power transfer theorem
Monitoring Devices Devices that monitor traffic flow on interstate roadways help reduce congestion near cities. For improved traffic control, monitoring devices flash your speed as you approach, warning you when you are over the limit and persuading you to slow down. Such devices are useful in construction zones where reduced speeds are required to protect workers.
Electric circuits have similar tools: current-monitoring devices that detect excessive currents and disconnect components that would be damaged if power limitations are exceeded. These circuit breakers in homes or office buildings have cutoff features that can be reset to restore service.
Measuring and regulating current flow in a circuit is as important as ensuring traffic flows freely. In this chapter, we use the superposition concept to calculate currents flowing in an electric circuit due to multiple sources. We form a simple equivalent circuit for parts of circuits that remain ...