1. Warm-up
How much power is dissipated by an electric heater connected to a 120V outlet when a current of 12 amps passes through it?
What are electric components? Name them.

2. Electric circuits
A circuit is the path through which current flows from the positive terminal of a battery via various electric components.

3. Circuit arrangement There are two types of circuit arrangement
series arrangement
Parallel arrangement

4. 1. Series arrangement
The path of the current is only one from the source through and all of the loads and back to the source.

5. Total Resistance
The total resistance is calculated using the formula:

6. Total Resistance=equivalent Resistance
equivalent resistance is when all the resistors are replaced by Total resistance.
Instead of the three resistors, we have one resistor with equivalent resistance of 18kΩ

7. Total current Total current is:
Remember Ohm’s law ?
Series circuits have Same amount of current through all resistors

8. Voltage drop across loads
The voltage drop across R1, R2, and R3 is:
V1 =IR1=
V2 = IR2=
V3 = IR3=
Total voltage;
VTotal= V1+ V2+ V3……
Each of the load or resistor will drop some voltage. (Voltage is shared)

9. Example
Two resistors 3Ω and 2Ω are connected in series to a 6-V battery.
Calculate the total resistance.
Calculate the amount of current through each resistor.
Calculate the voltage drop across each resistor.

10. Question
What happens to the total current when more devices are added to a series circuit?

11. Class work
Textbook pg 559 # 1-5, 16, 18-21

12. 2. Parallel arrangement Light bulbs arranged Parallel to each other.
The voltage is equal across all components in the circuit . Each of the bulb is drawing the same amount of voltage.

13. Total Resistance The Total resistance is given by: Or
When loads or resistors are arranged in parallel, their Combined resistance decreases.
The Total resistance is given by: Or

14. Example
Calculate the combined resistance of the circuit below

15. Current in parallel circuit
Current is shared amongst the resistors/load such that total current;

16. Example
Calculate the current through each one of the three resistors in the circuit below.
Solution:

17. Question
What happens to the total current resistance when more devices are added to a Parallel circuit?
Why does the total circuit resistance decrease when more devices are added to a parallel circuit?

18. Class work/Homework Class work: Pg 560 # 17, 22-29
Homework: Pg 560 # 6-15