The Student Room Group

Resistance of circuits

Please help me to understand why the answer of c) ii) is 1:2.
I thought R2 would get 6V since it is in parallel and then the voltage will be divided between R1 and R3 since they are in series.
Screenshot 2023-10-19 234916.png
(edited 6 months ago)
Reply 1
The total resistance of R1 and R2 wil be R/2 (R1=R2=R) so in series with R gives the pd ratio is ...
(edited 6 months ago)
Reply 2
Original post by mqb2766
The total resistance of R1 and R2 wil be R/2 (R1=R2=R) so in series with R gives the pd ratio is ...

I'm sorry. I still don't understand. Could you explain why this assumption of mine is wrong:


"I thought R2 would get 6V since it is in parallel and then the voltage will be divided between R1 and R3 since they are in series."


Am I misunderstanding the circuit arrangement? Is R1 in series with R3 and R2 is also in series with R3?
Reply 3
Original post by S0303
I'm sorry. I still don't understand. Could you explain why this assumption of mine is wrong:


"I thought R2 would get 6V since it is in parallel and then the voltage will be divided between R1 and R3 since they are in series."


Am I misunderstanding the circuit arrangement? Is R1 in series with R3 and R2 is also in series with R3?

R1 and R2 (both equal to R) are in parallel so they can be replaced by a single, equivalent resistor R12 = R/2. Then R12 is then in series with R3 and the pd is split across these two resistors accordingly.

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