1. ECE 201 Circuit Theory I1 Impedance and Reactance In general, Resistance Inductance Capacitance Z = Impedance

2. ECE 201 Circuit Theory I2 Definitions for Impedance Impedance in the frequency domain is analogous to resistance, capacitance, and inductance in the time domain The imaginary part of the impedance is called the “Reactance” The units of Impedance and Reactance are Ohms

3. ECE 201 Circuit Theory I3 Impedance and Reactance Values Circuit Element Resistance Inductance Capacitance Impedance Reactance R -------------- jωL ωL j(-1/ωC) -1/ωC

4. ECE 201 Circuit Theory I4 Assessment Problem #9.3 The current in a 20 mH inductor is 10cos(10,000t+30  )mA. Calculate the inductive reactance ωL = (10,000)(20X10 -3 ) = 200 Ω Calculate the impedance of the inductor jωL = j200 Ω Calculate the phasor voltage V V = (200  90  )(10X10 -3  30  ) = 2  (120  )

5. ECE 201 Circuit Theory I5 Assessment Problem #9.3 (continued) Calculate the steady-state expression for the inductor voltage v(t) v(t) = 2cos(10,000t+120  ) volts