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# Electrical circuits question watch

1. Hey,
If possible can I please have a bit of help on this question.

Two cells having an emf of 3.0 V and an internal resistance of 5 ohms are connected in series. Determine the current flowing in the circuit when cells are connected to a 10 ohms external resistor.

I know for circuits in series that the current through components is the same for each componenent but that the only start I have made.
2. In this situation, you can just consider the internal resistances as if they are external resistors. Do you know how to combine voltage sources and resistors in series?
3. (Original post by HandmadeTurnip)
In this situation, you can just consider the internal resistances as if they are external resistors. Do you know how to combine voltage sources and resistors in series?
Is it Rtotal = R1 + R2 + R3?

or

e(emf) = IR + Ir?
4. (Original post by RHCPfan)
Is it Rtotal = R1 + R2 + R3?

or

e(emf) = IR + Ir?
The first one. You can just consider the circuit as two voltage sources in series with three resistors. Then you can combine everything to end up with a single voltage source in series with a single resistor. After that, it's just a simple case of using I=V/R to find the current.
5. (Original post by HandmadeTurnip)
The first one. You can just consider the circuit as two voltage sources in series with three resistors. Then you can combine everything to end up with a single voltage source in series with a single resistor. After that, it's just a simple case of using I=V/R to find the current.
Ok I will give it a try. Unsure because I missed when we covered this
6. (Original post by HandmadeTurnip)
The first one. You can just consider the circuit as two voltage sources in series with three resistors. Then you can combine everything to end up with a single voltage source in series with a single resistor. After that, it's just a simple case of using I=V/R to find the current.
I get I = 0.3 A, is that correct?
7. (Original post by RHCPfan)
I get I = 0.3 A, is that correct?
Yes.
8. (Original post by HandmadeTurnip)
Yes.
Great! Thank you very much for your help.

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