1. Section 3—Electrical Energy
To use electrical energy, a complete circuit must be made
Series Circuit—current has only one loop to flow through
*Used in flashlights and some holiday lights

2. (Circuit types continued)
Open circuit—when any part of a series circuit is disconnected, no current flows through the circuit
Ex: when 1 X-mas bulb is out, the whole string is out!!

3. Parallel Circuits
Parallel circuits—contain two or more branches for current to move through.
Advantages:
When one branch of the circuit is opened, the current continues to flow through other branches
Ex: rooms in houses, cars, etc.
Fig. 18 on pg. 210

4. Household Circuits
In most homes, wiring is organized and logically connected
Wiring is hidden behind walls, under floors, etc.
Standard voltage difference in US is 120 V
There is a main switch and circuit breaker/fuse box for homes
Parallel circuits branch out to rooms/appliances

5. (more on household circuits)
Many houses draw current from the same circuit
As the amount of current increases, so does the amount of heating in the wires
If wires get too hot, insulation melts and bare wires can cause a fire
For protection, homes have fuses or a circuit breaker

6. Fuses and Circuit Breakers
Fuses—small pieces of metal that melt if current becomes too high, and causes a break in the circuit, current flow stops
Circuit breaker—contains a switch to flip and open the circuit, stopping the flow of current/usually can be reset by moving switch to its “on” position

7. Electrical Power
Electrical power—the rate at which electrical energy is converted to another form of energy
Used by appliances/varies
Calculating Power:
POWER = CURRENT X VOLTAGE DIFFERENCE OR
P(watts) = I (amperes) X V (volts)

8. Electrical Energy
The amount of electrical energy you use depends on two things:
Power required by appliances in your home
How long the appliances are used
Calculating Energy:
ENERGY = POWER x TIME OR
E(kWh) = P (kW) x T(h)

9. Kilowatt Hours Kilowatt-hour = the unit of electrical energy
One kilowatt= 1,000 Watts
SECTION REVIEW QUESTIONS