# Parallel Circuits 8 Note Boxes. Quick Review The electrons that move to make electricity come mostly from the wires in the circuit, not the battery. Metals.

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Parallel Circuits 8 Note Boxes

Quick Review The electrons that move to make electricity come mostly from the wires in the circuit, not the battery. Metals are conductors because their electrons can move. Box #1

Introduction There are two network configurations – series and parallel. Last class we covered a series network. In this lesson we will cover the parallel circuit and all the methods and laws associated with it.

Do You Remember? What did we say was the biggest DISADVANTAGE of using a series circuit?

Branching Out Parallel circuits have independent paths. We call these independent paths branches. Box #2-3 notes

Junctions Junction: Where the branches join or split B1B2B3B4 Box #2-Cont

Parallel Circuit Advantage In a parallel circuit, each device operates independent of the other devices. A break in any one path does not interrupt the flow of charge in the other paths. Box #3

Independent Paths

Which one? Which switch, if opened, will cause the light bulb to stop glowing? Why?

Which circuit is built so that if one light bulb goes out, the other three light bulbs will continue to glow?

Voltage in Parallel Circuits The batteries are typically in series with one another. The total voltage therefore is found by adding up each individual battery. The total voltage going across each branch is the same. Box #4- 2 notes

That was Easy… Now heres is where things start to change from a series circuit The total current divides among the parallel branches Huh? Remember Ohms Law? Box #4-Cont

Ohmss Law (Amps) (volts) (ohms)

Comparing and Contrasting Series vs Parallel If theyre all in a row (series), you just add them up and go! If they have a different road (parallel), take the time to break the code. Box #5- Technically 2 notes

Current in Parallel Circuits

Resistance in Parallel Circuits From the batterys perspective, the overall resistance of the circuit is decreased. This means the overall resistance of the circuit is less than the resistance of any one of the branches. Box #6-2 notes

think! What happens to the light intensity of each lamp in a parallel circuit when more lamps are added in parallel to the circuit? Resistance in Parallel Circuits

think! What happens to the light intensity of each lamp in a parallel circuit when more lamps are added in parallel to the circuit? Answer: The light intensity for each lamp is unchanged as other lamps are introduced (or removed). Although changes of resistance and current occur for the circuit as a whole, no changes occur in any individual branch in the circuit. Parallel Circuits

Parallel Resistors For resistors in parallel, the total resistance is determined from Box #6- Cont

Ready to rip your hair out yet? There IS an easier way…

Circuit Overload To prevent overloading in circuits, fuses or circuit breakers are connected in series along the supply line. Box #7

Brain Break-Fuses When you blow a fuse, what does that mean? Electricity through a circuit causes heat. Fuses melt (or break) when too much current passes through it; they must be replaced. This protects expensive electronic equipment. Box #8-2 notes

Circuit Breakers Circuit Breakers protect against too much current like fuses, but can be reset. Box #8-Cont

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