#### Transcript Document

```Admin:
• Assignment 7 is posted
• Due Monday (20th)
• Hints:
• For capacitors in series, the charge is the same
• For capacitors in parallel the voltage is the same
• Second mid-term date is set:
• Wednesday May 6th
http://apod.nasa.gov/apod/ap110102.html
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Impedance is the complex form of a component’s resistance
Capacitative Impedance
Inductive Impedance
Resistive Impedance
1
ZC =
jwC
Z L = jw L
ZR = R
What if there is more than one component?
AC circuit analysis
• Procedure to solve a problem
– Identify the source sinusoid and note the frequency
– Convert the source(s) to complex/phasor form (you can ignore the ωt component
at this point)
– Represent each circuit element by it's AC impedance. Impedances add like
resistors.
– Solve the resulting phasor circuit using standard circuit solving tools (equivalent
impedances, voltage/ current divider, KVL,KCL,Mesh, Thevenin etc.)
Impedances combine like restances in a DC circuit.
– Find the real part of the solution, and write it as a function of time.
This circuit contains an AC current source is(t)=10cos2t Amps.
Use the generalized Ohm’s law to find the voltage, v(t).
Note the
frequency
Note: the regular number “1” is the complex number “1+0j ”
j2 = -1
Now switch to
phasor form to
make life easy
Amplitude A=16.67 Volts
v(t)
is(t)