1. Circuits
Any complete path along which electrons (charge, current) can flow.
Can be arranged in series or in parallel

2. Parts of a Circuit

5. A battery converts chemical energy into electrical energy
A battery converts chemical energy into electrical energy. It provides voltage.
A resistor (lamp, toaster) uses the electrical energy that travels through the circuit. It converts electrical energy to heat energy.
A switch opens or closes a circuit.

6. A fuse or a circuit breaker will open or close a circuit if too much current is passing through it.

7. A voltmeter measures how much potential energy is dropped off at a resistor. Drawn across a resistor and must have high resistance itself.
An ammeter measures how much current is running through it. Drawn directly in a circuit and have low resistance.

8. Series Circuits

9. Series Equations The current is the same everywhere. I = I1 = I2 = I3
The total voltage of the circuit is the voltage of the battery and a portion of the voltage is dropped off at each resistor. How much depends on the resistance (V= IR)
V = V1 + V2 +V3

10. The equivalent resistance of the circuit is the total resistance of the circuit.
Req = R1 + R2 +R3
Req = VT IT

11. Examples
Three resistors of 5 Ω, 10 Ω and 15 Ω,respectively, are connected in series to a 24 V battery. Determine:
the equivalent resistance
the current through each resistor
the potential drop across each resistor

12. Given the circuit below determine:
the total current and the current through both resistors. The voltage of the battery is 12 V and R1 = 40 Ω and R2 = 80 Ω

13. Determine the readings of the ammeters and voltmeters in the circuit

14. Series Summary
The Req is the sum of all the resistances in the circuit.
The equivalent resistance of a series circuit as more resistors are added.
The total current of a series circuit as more resistors are added.
The current is the same everywhere.

15. The sum of all the voltages in the circuit is the voltage of the battery.

16. Parallel Circuits

17. Parallel Equations
The current is the sum of the current in each branch.
I = I1 + I2 + I3
The current at each branch depends on V and R. (I= V/R)
The voltage dropped off at each resistor is the same as the voltage of the battery.
V = V1 = V2 = V3

18. The equivalent resistance is the total resistance of the circuit.

19. Three resistors of 8 Ω, 12 Ω and 24 Ω are connected in parallel to an applied potential difference of 24 V. Determine:
The equivalent resistance of the circuit
The potential difference across each resistor
The current through each resistor

20. Determine the readings of the voltmeters and ammeters.

21. Parallel Summary Req is
The equivalent resistance of a parallel circuit as more resistors are added.
The total current of a parallel circuit as more resistors are added.
The total current is the sum of the currents in each branch.

22. The voltage through each branch is the voltage of the battery
Home appliances are generally connected in parallel. If too many appliances are used at once, the overall of the circuit decreases, the increases and a blows.

23. If 10 lit light bulbs are connected in series, and then 1 bulb is removed from the circuit. What happens?
If 10 lit light bulbs are connected in parallel, and then 1 bulb is removed from the circuit. What happens?

26. Junctions
A junction is a part of a circuit where current enters and leaves.
According to the Law of Conservation of Charge, the total amount of current entering a junction must = the sum of the current leaving a junction.