1. Simple Resistive Circuites
Lecture 3

2. Resistors in Series
Series-connected circuit elements carry the same current
The seven resistors can be replaced by a single resistor

3. Examples (Series):

4. Resistors in Parallel
Parallel -connected circuit elements have the same voltage across their terminals

5. Resistors in Parallel
Two resistors

6. Examples (Parallel):

7. Equivalent Resistance

8. Equivalent Resistance
30 Ω
5 kΩ
80 Ω

10. (p3.5, p3.6, p3.7, and assessment problem 3.1)
Use Ohm’s law, KCL & KVL
H.W. #4
(p3.5, p3.6, p3.7, and assessment problem 3.1)
15kΩ
75W
192W
500W

11. Voltage-divider circuits

12. Assessment Problem 3.2

14. Current-divider circuits

16. Assessment Problem 3.3

17. H.W. #5
(Assessment problem 3.4, p3.15(a, b))

18. Measuring Voltage and Current Digital meters and Analog meters
An Ammeter: instrument to measure current.
Placed in series with the circuit element whose current is being measured.
A Voltmeter: instrument to measure voltage.
Placed in parallel with the circuit element whose voltage is being measured.
Two categories of meters used to measure voltage and current:
Digital meters and Analog meters

19. Measuring Resistance: The Wheatstone Bridge
is a circuit used to precisely measure resistance of medium values in the range of 1Ω to 1M Ω.
Consists of four resistors, a dc voltage source, and a detector (galvanometer).
One of the four resistors can be varied (R3).
To find the value of Rx, we adjust the variable resistor R3 until there is no current in the galvanometer. We then calculate the unknown resistor from the simple expression:

20. Delta-to-Wye (∆-to-Y)(Pi-to-Tee) equivalent circuits
The interconnected resistors can’t be reduced by the simple series or parallel equivalent circuits
A ∆ configuration viewed as π configuration
A Y structure viewed as T structure
∆-to-Y equivalent circuit
Y -to- ∆ equivalent circuit

22. Assessment Problem 3.8

23. H.W. #6
3.55, 3.56(a & b)