1. C H A P T E R 20 Electric Circuits

2. 20.6 Resistances in Series

3. Personal Electronic Assistants PEA or PDA

4. Resistances in Parallel

5. Series and Parallel Wiring
When resistors (R1, R2, R3) are connected in series the equivalent resistance (Rs) is given by,
When resistors (R1, R2, R3) are connected in parallel the equivalent resistance (Rp) is given by,

6. 20.7 Parallel Wiring

7. 20.8. Circuits Wired Partially in Series and Partially in Parallel
Problem 61, p615:
Determine the equivalent resistance between the points A and B for the group of resistors in the drawing.

8. 20.9. Internal Resistance
So far, the circuits we have considered include batteries that contribute only their emfs to a circuit.
In reality, however, batteries also add some resistance. This resistance is called the internal resistance of the battery.
In a battery, the internal resistance is due to the chemicals within the battery.