1. Notes on Chapter 35 Electric Circuits
Conceptual Physics
Notes on Chapter 35
Electric Circuits

2. Electric Circuits
Any path in which electrons flow is a Circuit. There can be no gaps in the flow of electrons.

3. Electric Circuits
A gap in the circuit is known as an Open Circuit. Electrons will not flow.
A Closed Circuit is when the flow of electrons is possible.

4. Electric Circuits
Most circuits have more then one devise that receives electrical energy. These connections are in either:
Series
Parallel

5. Electric Circuits SERIES CIRCUITS:
Fig shows three lamps in series connected to a power supply --- a battery.
Electric current has ONLY a single path through the circuit.
Resistance is the TOTAL resistance of each lamp or resistor along the pathway.
The current is equal to the voltage source divided by the total resistance (Ohm’s Law)
As the number of lamps is added, the resistance is INCREASED.
The disadvantage of a series circuit is if one lamp fails (burns out) the whole circuit fails.

6. Electric Circuits PARALLEL CIRCUITS:
Fig shows three lamps connected in parallel.
Each lamp connects the same two points. Therefore, the voltage is the same across each device.
The amount of current in each lamp is the same.
Total current in the circuit equals the SUM of the currents in each pathway.
As the number of lamps is added, the resistance is DECREASED.

7. Electric Circuits
SCHEMATIC DIAGRAMS:
See Fig on page 554.

8. Electric Circuits
Battery
SINGLE (Cell)
DOUBLE HIGH
(Battery) VOLTAGE

9. Connecting wire – Black line
Electric Circuits
Connecting wire – Black line

10. Electric Circuits
Open switch

11. Electric Circuits
Closed switch

12. Electric Circuits
Resistance

13. Electric Circuits COMBINING RESISTORS: Series and Parallel
See Fig. 35.8

14. Electric Circuits
When in series, the resistance ADDS up to a larger resistance.
Very bright Bright Dimmest

15. Electric Circuits
When in Parallel, the resistance SUBTRACTS to a smaller resistance.
Bright Same Bright Same Bright

16. Electric Circuits
When lines carry too much current, the heat may melt the wire and start a fire.
Fuses or Circuit breakers are used to prevent an overload in the wire.