1. Chapter 19: Electric Charges and Currents
Electric Circuits and Electric Power

2. Electric Circuits
An electric circuit provides a complete, closed path for an electric current.
An electric circuit consists of a source of energy (voltage source), a load (resistance), wires, and a switch

3. Electric Circuits
Source: battery, thermocouple, etc.
Load: uses electric energy (light bulb, appliance, etc.) - offers some resistance to current flow
Switch: opens and closes the circuit
A current needs a closed path - if a switch is off, the circuit is open.

4. Parts of an Electric Circuit
Source (Battery)
Load (Light Bulb)

5. Electric Circuits
Electricity cannot flow through an open circuit. Electricity can only flow through a closed circuit.
Closed Circuit
Open Circuit

6. Series and Parallel Circuits
Series Circuit: circuit in which all parts are connected one after another. If there is a break, the entire circuit is opened and no current flows
Parallel Circuit: circuit in which different parts are on separate branches. If there is a break, electrons can still move.

7. Series and Parallel Circuits

8. Series Circuit

9. Parallel Circuit

10. Series and Parallel Circuits
Fuse: this strip of metal used for safety because when the current flowing through it becomes too high, it melts and breaks the flow of electricity
- Protects against too much current flow (overload)
- Once fuses burn out they must be replaced

11. Series and Parallel Circuits
Circuit Breaker: reusable device that protects a circuit from being overloaded
- Easier to use than fuses

12. Power = Voltage x Current
Electric Power
Electric Power is the ratio at which electric energy is used by doing work, or by changing to a different form, such as heat or light
Power = Voltage x Current
P = V x I
Watts = Volts x Amperes

13. Kilowatt-hours = Kilowatts x hours
Electric Energy
Energy = Power x Time
E = P x t
Kilowatt-hours = Kilowatts x hours