Lecture 10

1.

RL Circuits
OEk 1115 - Fundamentals of Electronics
Lecture 10

2.

Outline
Series RL Circuits
Parallel RL Circuits
Series-Parallel RL Circuits

3.

Impedance of Series RL Circuits
The impedance of a series RL circuit is the total opposition to sinusoidal current
and its unit is the ohm.

4.

Impedance of Series RL Circuits
Example. Determine the impedance of the circuit.

5.

Analysis of Series RL Circuits
Ohm’s law and Kirchhoff’s voltage law are used in the analysis of series RL
circuits to determine voltage, current, and impedance.
The application of Ohm’s law to series RL circuits involves the use of the
quantities of Z, V, and I.
The three equivalent forms of Ohm’s law for RC circuits apply also to RL circuits
and are stated here:

6.

Analysis of Series RL Circuits
Example. The current in the circuit is 200 uA. Determine the source voltage
(u: micro).

7.

Analysis of Series RL Circuits
Solution.

8.

Phase Relationships of the Current and Voltages
In a series RL circuit, the current is the same through both the resistor and the
inductor.
From Kirchhoff’s voltage law, the sum of the voltage drops must equal the source
voltage.

9.

Phase Relationships of the Current and Voltages
Example. Determine the source voltage.

10.

Impedance of Parallel RL Circuits

11.

Impedance of Parallel RL Circuits
Example. Determine the impedance.

12.

Impedance of Parallel RL Circuits
Solution.

13.

Conductance, Susceptance, and Admittance

14.

Conductance, Susceptance, and Admittance
Example. Determine the total admittance for the circuit.

15.

Solution.

16.

Analysis of Parallel RL Circuits
Ohm’s law and Kirchhoff’s current law are used in the analysis of RL circuits.
Current and voltage relationships in a parallel RL circuit are examined.
Example. Determine the total current in the circuit.

17.

Solution.

18.

Series-Parallel RL Circuits
Example. In the series-parallel RL circuit, determine the values of the following:
a) Z(tot)
b) I(tot)

19.

20.

21.

Q&A
Any Questions?