1. Electric Current
Chapter 22-2

2. What is Electric Current?
Flow of electric charge
Source of electric energy that can be controlled
Solids—flowing charges; electrons
Liquids—flowing charges; ions
Measured in units of amperes (A)

3. Electric charges will flow continuously only through a closed connecting loop called a circuit.

4. Electric Circuits Simplest electric circuit
Battery—source of electrical energy
Wire—electric conductor

5. Current will flow in the circuit as long as none of the wires (including filament in bulb) is disconnected or broken.
Broken circuit
Working circuit

6. Electrons move away from the negative battery terminal toward the positive terminal

7. Voltage
Measure of how much electrical potential energy each electron can gain
Voltage increases—electric potential energy increases
Measured in Volts (V)

8. Batteries Supplies energy to an electric circuit
When positive and negative terminals are connected in a circuit, the electric potential energy is increased
Supplies energy by converting chemical energy to electric potential energy

9. Alkaline Batteries +/- separated by a moist paste
Chemical reactions occur in the paste when a current is added
Produces an electric field in circuit
Batteries contain only a limited amount of chemicals to produce energy
Once original chemicals are used up—”dead”

10. Resistance
Measure of how difficult it is for electrons to flow through material
Measured in ohms (Ω)

11. Insulators generally have higher resistance than conductors
Thinner wires—higher resistance
Longer wires—higher resistance
Copper wire—low resistance, good conductor
Used in homes because wires do not get hot enough to cause fire