1. ELECTRICAL CIRCUITS
All you need to be an inventor is a good imagination and a pile of junk.
-Thomas Edison

2. Would This Work?

3. Would This Work?

4. Would This Work?

5. The Central Concept: Closed Circuit

6. Current: continuous flow of electric charges through a material
High Current (low voltage)
Low Current (high voltage)

7. Voltage- difference in electric potential between two points (push that causes electrons to move)
Low Voltage
High Voltage

8. Resistance: measure of how difficult it is for charges to flow through the objects

9. Simple Circuits Series circuit Parallel circuit All in a row
1 path for electricity
1 light goes out and the circuit is broken
Parallel circuit
Many paths for electricity
1 light goes out and the others stay on

10. circuit diagram
Scientists usually draw electric circuits using symbols;
Battery (cell)
Light (resister)
switch
wires

11. Ohm’s Law Simple analogy: Water in a hose
Electrons in a copper wire are analogous to water in a hose.
Consider the pressure valve as the applied voltage and the size of the hose as the source of resistance.
The absence of pressure in the hose, or voltage across the wire will result in a system without motion or reaction.
A small diameter hose will limit the rate at which water will flow, just as a small diameter copper wire limits the flow of electrons. 3

12. Ohm’s Law Voltage = Current x Resistance Current (amps)= Voltage
Georg Simon Ohm ( )

13. Ohm’s Law
Current (amps)= Voltage
Resistance
the greater the voltage (or pressure) across a resistor, the more the current.
The more the resistance, for the same voltage, the less the current. 4

14. 1. How did adding more voltage affect the current (speed of motor)?
Lab Questions:
1. How did adding more voltage affect the current (speed of motor)?
2. How did adding more resistance (lights + motor) affect the current (speed)?

15. PARALLEL CIRCUIT
Place two bulbs in parallel. What do you notice about the brightness of the bulbs?
Add a third light bulb in the circuit. What do you notice about the brightness of the bulbs?
Remove the middle bulb from the circuit. What happened?

16. measuring current
Electric current is measured in amps (A) using an ammeter connected in series in the circuit. A

17. measuring current A A This is how we draw an ammeter in a circuit.
PARALLEL CIRCUIT
SERIES CIRCUIT

18. measuring voltage
The ‘electrical push’ which the cell gives to the current is called the voltage. It is measured in volts (V) on a voltmeter V