This document discusses electric circuits, including series and parallel circuits. For series circuits, the equivalent resistance is calculated by adding all resistor values. For parallel circuits, the equivalent resistance is calculated using the reciprocal of the sum of the reciprocals of the individual resistances. It also covers Delta-Star-Delta conversions and using voltage divider rules to find the current through a specific resistor in a circuit. Examples are provided and students are directed to other resources for additional practice.

1. Chapter (2)
Electric Circuits
Series & Parallel Circuits
Delta – Star – Delta conversions
Voltage Divider Rules
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Series Circuits
For multiple resistors in series, add all values:
R equivalent = R1 +R2 +R3 … Rn
Note: 2 resistors are considered in series, if the same
current passes through both of them.

3. Parallel Circuits
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For multiple resistors in parallel,
1/R eq = 1/R1 + 1/R2 + 1/R3 … 1/Rn
Note:
2 resistors are considered in //, if their two terminals are the same
(same voltage)

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Illustrated Example: How to get the equivalent resistance?

5. Equivalent resistance is important in circuit
analysis applications
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Find the current passing through the resistor 10 ohm?

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8. Examples
Refer to lecture notes to see more examples
Refer to assignment (2) for more practice
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9. Delta- Star- Delta Conversions
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To convert from Delta to Star:
To convert from Star to Delta:

10. • Refer to lecture to see more than three or four
examples.
• Refer to tutorial to see more and more cases.
• Homework: Sheet (2)
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