1. April 24th, 2006
AC Circuits
PHYS 102
Alternating Current (AC) circuits. So far we have been talking about Direct Current.

2. PHYS 102 angular frequency phase amplitude
April 24th, 2006
AC Circuits
PHYS 102
Time varying currents can be produced by time varying voltages. (Like that supplied by the wall socket)
Recall: need to identify amplitude, frequency, and phase constant for sinusoidal functions.
New symbol: AC voltage source.
amplitude
phase
angular frequency

3. We restrict our discussion to sinusoidally varying currents.
April 24th, 2006
AC Circuits
PHYS 102
We restrict our discussion to sinusoidally varying currents.
amplitude
angular frequency
phase

4. Does it make sense to talk about averages?
April 24th, 2006
AC Circuits
PHYS 102
Does it make sense to talk about averages?
To discuss averages for sinusoidal functions, one would obtain a value of zero!
Yet, the wall socket value of 120V is a type of average.

5. PHYS 102 Does it make sense to talk about averages?
April 24th, 2006
AC Circuits
PHYS 102
Does it make sense to talk about averages?
Answer: YES! (But we need to discuss a root mean square average).

6. April 24th, 2006
AC Circuits
PHYS 102
Root mean square (RMS):

7. PHYS 102 Where AC Circuits T is the period of oscillation.
April 24th, 2006
AC Circuits
PHYS 102
Where
T is the period of oscillation.