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Resistive Circuits
ELEC 308
Elements of Electrical Engineering
Dr. Ron Hayne
Images Courtesy of Allan Hambley and Prentice-Hall
Series Resistances
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Parallel Resistances
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Combining Resistances
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Exercise 2.1
 Find Req
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Electrical Network Analysis
 Electrical network is another name for an
electrical circuit

Circuit elements connected together in closed
paths
 Network analysis

Process of determining the current, voltage, and
power for each element given the circuit diagram
and element values
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Equivalent Circuit Analysis
1. Find a series or parallel combination of resistances,
typically the farthest away from the source.
2. Redraw the circuit with the equivalent resistance in place
of the combination selected in step 1.
3. Repeat steps 1 and 2, reducing the circuit as far as possible.
Usually, we end up with a single source and a single
resistance.
4. Solve for the currents and voltages in the final equivalent
circuit. Then go back one step and solve for the unknown
currents and voltages. Continue doing so until you reach
the original circuit and have determined all the currents and
voltages.
5. Check that KCL is satisfied at each node, KVL is satisfied
for each loop, and conservation of energy (power) law is
satisfied for all elements in the circuit.
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Network Analysis Example
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Network Analysis Example
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Exercise 2.2
 Find ik
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Voltage-Division Principle
 Of the TOTAL voltage, the fraction that appears
across a given resistance in a SERIES circuit is the
ratio of the GIVEN resistance to the TOTAL series
resistance.
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Voltage-Divider Exercise
 Find vk
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Position Transducers
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Current-Division Principle
 For TWO resistances in PARALLEL, the fraction
of the TOTAL current flowing in a resistance is the
ratio of the OTHER resistance to the SUM of the
two resistances.
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Current-Divider Exercise
 Find i1
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Exercise 2.3
 Find vk
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Exercise 2.4
 Find ik
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Application Exercise
 Find i3
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Summary
 Equivalent Resistance


Series
Parallel
 Network Analysis



KVL
KCL
Ohm’s Law
 Voltage-Division
 Current-Division
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