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

2. 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?

3. Impedance Matching

4. Transmission of power

5. Alternating Current (AC) Circuits

6. Root Mean Square (rms) Values

7. Power in an AC circuit

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

9. Capacitors in AC circuits
Inductors in AC circuits

10. 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

11. RC Circuits in AC
RL Circuits in AC

13. Resonance in RLC circuits

15. Selectivity and Q of a Circuit

16. 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.