Dynamic Electricity and Electromagnetism — Chapter 4: AC circuits

About this lesson

This unit covers the measurement of alternating current using a hot wire ammeter, explaining its construction, operation, calibration, and disadvantages. It then explores AC circuits containing pure ohmic resistance, pure inductive coils, and pure capacitors, deriving the phase relationships between voltage and current in each case, and introducing the concepts of inductive reactance and capacitive reactance. The unit also covers series and parallel combinations of inductors and capacitors, and defines impedance for RL, RC, and LCR series circuits, including how to calculate total voltage and phase angle. Finally, it discusses the oscillating (LC) circuit, energy exchange between electric and magnetic fields, and the resonant (tuned) circuit, including its frequency formula and application in radio receivers. By the end, a student should be able to describe the operation of a hot wire ammeter, calculate reactances and impedance, determine phase relationships, and solve problems involving AC circuits and resonance.