# Section 3—Electrical Energy

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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

(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!!

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

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

(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

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

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)

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)

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