Alternating Current (AC) Chapter 2 Alternating Current (AC) Transformer

Example 2.1 A step-up transformer has 25 turns on the primary coil and 500 turns on the secondary coil. If this transformer is to produce an output of 4800 V with a 12-mA current, what input current and voltage are needed?

Impedance Matching

Transmission of power

Alternating Current (AC) Circuits

Root Mean Square (rms) Values

Power in an AC circuit

AC circuits and Impedance Impedance ( Z ) Resistance Capacitive Reactance Inductive Reactance R Xc XL 1 / C L  = 2 p f

Capacitors in AC circuits Inductors in AC circuits

Resistor Capacitor Inductor The capacitor voltage 90o lags the current The inductor voltage 90o leading the current The resistor voltage is in phase with the current

RC Circuits in AC RL Circuits in AC

Resonance in RLC circuits

Selectivity and Q of a Circuit

Metal Detectors in Airports The metal detector is essentially a resonant circuit. The portal you step through is an inductor (a large loop of conducting wire) that is part of the circuit. The frequency of the circuit is tuned to the resonant frequency of the circuit when there is no metal in the inductor. When you walk through with metal in your pocket, you change the effective inductance of the resonance circuit, resulting in a change in the current in the circuit. This change in current is detected, and an electronic circuit causes a sound to be emitted as an alarm.