1. Series and Parallel Circuits

2. Reminder Voltage (V): electrical potential difference
Electrical potential energy a single unit of charge gains as it passes through a source (battery)
Current (I):
Flow of electrical charge
Measured in Amperes
Load:
Resists the flow of electrons
As electrons pass through a load, they lose energy as electrical energy is transformed to another type of energy (sound, heat, light, mechanical, etc.)
Resistance (R):
Describes the amount that current is hindered by a load
Measured in Ohms (Ω)

3. First we need to know what we are looking at!

4. Component
Symbol
Quantity
Unit of Measurement
Source
Cell
Electrical Potential Difference (V)
Volt (V)
Battery
Conducting Wire
Current (I)
Ampere (A)
Load
Resistance (R)
Ohm (Ω)
Switch
Open
Closed
Ammeter
Measures amperes
Voltmeter
Measures volts

5. Series vs Parallel Circuits
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6. A circuit in which current can only flow along ONE path.
Current is equal at all points in the circuit.
voltage across the circuit is the sum of the voltages across each load.
The voltages across loads in a series circuit will always equal the source voltage.
The resistance of all the loads in series add together.
Example of a series circuit:
Some decorative lights are connected in such a way that if one bulb burns out the rest of the lights won’t work.
Series Circuit

7. A circuit that has at least one branch point where the current splits into two or more pathways.
Current is changed as it enters a branch. Current across branches is the sum of the currents across all branches.
Voltage across each of the loads (branches) is unchanged.
Resistance in the circuit is reduced due to multiple pathways for electrons to flow.
Example of a parallel circuit:
Appliances in your kitchen are connected so that if one appliance is turned off the rest will work.
Parallel Circuit

8. Where would you see a SERIES CIRCUIT in every day life?
Think about it
Where would you see a SERIES CIRCUIT in every day life?
Where would you see a PARALLEL CIRCUIT in every day life?

9. Circuits in your House
In parallel circuits each device is controlled by its own switch without shutting off the others. When all the devices are on, a large amount of current is passing through the conductor near the source.

10. Think about your home. Would having only one parallel circuit be convenient?
Issues that would arise?
What do we have to fight this problem?

11. When large amounts of current flow through a wire, it can get very hot and it becomes a safety hazard.
In buildings, such as your school and house, many separate parallel circuits are installed.
With this system large electrical cables carry electrical energy from a power source to the building. This is then connected to a circuit panel (fuse box), which connects to each of the parallel circuits inside the panel.
This separation of the parallel circuits helps to decrease the amount of current flowing through the conductors, which decreases the chance of a possible fire being caused by extremely hot wires.