1. Electrical Systems
Series Circuits
Parallel Circuits
Electrical Power

2. Electrical Power
Electrical power is measured in watts, just like mechanical power.
Power is the rate at which energy is changed into other forms of energy such as heat, sound, or light.
Anything that “uses” electricity is actually converting electrical energy into some other type of energy.

3. Important review

4. Electrical Power The watt is an abbreviation for one joule per second.
A 100-watt light bulb uses 100 joules of energy every second.

5. Power
Power is a “rate” and is measured using current and voltage .

6. Different forms of the Power Equation

7. Kilowatt
Most electrical appliances have a label that lists the power in watts (W) or kilowatts (kW).
The kilowatt is used for large amounts of power.

8. A 12-volt battery is connected in series to two identical light bulbs.
Solving Problems
A 12-volt battery is connected in series to two identical light bulbs.
The current in the circuit is 3 amps.
Calculate the power output of the battery.

9. Looking for: Given: Relationships: Solution: Solving Problems
…power of battery
Given:
…voltage = 12 V; current = 3 amps
Relationships:
Power: P = I x V
Solution:
P = 3 A x 12 V = 36 watts

10. Buying Electricity
Utility companies charge customers for the number of kilowatt-hours (kWh) used each month.
A kilowatt-hour is a unit of energy.
The number of kilowatt-hours used equals the number of kilowatts multiplied by the number of hours the appliance was turned on.