Circuits Combination for 9th Grade

Circuits Combination for IGCSE

by Azizah Mutiarani

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• Understand that the current at every point in a series circuit is the same

• Give the combined resistance of two or more resistors in series

• State that, for a parallel circuit, the current from the source is larger than the current in each branch

• State that the combined resistance of two resistors in parallel is less than that of either resistor by itself

• State the advantages of connecting lamps in parallel in a lighting circuit

• (S) Calculate the combined e.m.f. of several sources in series

• (S) Recall and use the fact that the sum of the p.d.s across the components in a series circuit is equal to the total p.d. across the supply

• (S) Recall and use the fact that the current from the source is the sum of the currents in the separate branches of a parallel circuit

• (S) Calculate the effective resistance of two resistors in parallel

​Learning Goals!

• A series circuit consists of a string of two or more components, connected end to end:​

Series Circuits​

​In a series circuit the current is the same at all points

Resistors in Series​

​Potential Difference in Series

​When several cells are connected together in series, their combined EMF is equal to the sum of their individual EMFs

​The total EMF of these cells is equal to the sum of their individual EMFs

​In a series circuit, the sum of potential differences across the components is equal to the total EMF of the power supply

​Parallel Circuits

• A parallel circuit consists of two or more components attached along separate branches of the circuit​

In a parallel circuit, the current splits up, dividing between the various branches of the circuit​

​Note that the current does not always split equally – often there will be more current in some branches than in others

​Resistors in Parallel

​Potential Difference in Parallel

​Try the simulation!

1. open https://phet.colorado.edu/sims/html/circuit-construction-kit-dc-virtual-lab/latest/circuit-construction-kit-dc-virtual-lab_in.html​

2. ​make your own series and pralllel circuits

​Lets Discuss !

​1. how the differences of the current between those circuits?

​2. how the differences of the potential differences?

​What is the combined resistance of a 2 Ω and a 3 Ω resistor connected in series?

​A parallel circuit has two identical resistors. A current of 4 A flows from the battery. What is the value of the current through each resistor?

​A series circuit has two identical resistors. A current of 4 A flows from the battery. What is the value of the current through each resistor?

​Three 5.0 ohm resistors are connected in series with a 12 V power supply. calculate the combined resistance of the three resistor, the current that flows in the circuit, and the p.d across each resistor !

​Summary !

I​n a series circuit the current is the same at all points

​A 4 ohm resistor and a 6 ohm resistor are connected in a series circuit with a 6 V power supply. calculate :

​1. the combined resistance of two resistors

​2. the current that flows in the circuit

​3. the p.d across each resistor