9 - Series And Parallel Circuits.ppt

Series and Parallel Circuits

Circuits In order for electricity to flow we need Power source Closed circuit

There are two type of circuits we will explore Series circuit Parallel circuit

Series Circuit In a series circuit there is only one path for the electrons to flow In other words all the components are in series with each other

Because there is only one path each charge will go through each resistor

Predict, Test and Explain • How will the brightness of the bulbs change as we add more in series?

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• What does this imply about the current in the circuit?

Parallel Circuit In a Parallel circuit there are multiple pathways for charge to flow Each device is placed on it’s own separate branch

Current goes through each of the branches at the same time

Predict, Test and Explain • How will the brightness of the bulbs change as we add more in parallel?

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• What does this imply about the current in the circuit?

Key Concepts Bulbs in series represent a source of resistance to current flow, similar to boulders in a stream which can block the flow of water Bulbs in parallel offer additional pathways for current flow, similar to branches of a stream which can carry more water.

Calculating Resistance in Series Circuits The rule for calculating Series Circuits is to… Add up the values of each individual in the series. R1 + R2 + R3… 5 + 5 + 10 20 Ω (ohms)

Calculating Resistance in Series Circuits Add up the values of each individual in the series. R1 + R2 + R3… 10 + 20 + 10 40 Ω (ohms)

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Calculating Resistance in Series Circuits  The rule for calculating Series Circuits is to…  Add up the values of each individual in the series.  1 1 1 1 -- = -- + -- + - 1 Rt R1 R2 R3 -- = 1  1 1 1 1 Rt -- = -- + -- + -Rt 4 4 2  1 -- = Rt  1 1 -- = .25 + .25 + .5 Rt  Rt = 1 Ω (ohms)  1 -- = 1 Rt  1 -- = 1 Rt

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Calculating Resistance in Series Circuits The rule for calculating Series

Circuits is to… Add up the values of each individual in the series. 1 1 1 1 -- = -- + -- + -• 1 Rt R1 R2 R3 -- = Rt 1 1 1 1 .016 -- = -- + -+ -Rt 100 200 1000 • Rt = 62.5 Ω (ohms) 1 -- = .01 + .005 + .001 Rt 1 -- = .016 Rt 1 -- = .016 Rt

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