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Seneka
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Homework Statement
https://www.bpho.org.uk/user/pages/05.past-papers/06.as-challenge/_general/BPhO_AS_2010_QP.pdf
12. A combination of resistors shown below represents a pair of transmission lines with a fault in
the insulation between them. The wires have a uniform resistance, but do not have the same
resistance as each other. The following procedure is used to find the value of the resistance R5.
With 1.5 V applied across terminals AC a current of 37.5 mA flows
With 1.5 V applied across terminals BD a current of 25 mA flows
With 1.5 V applied across terminals AB a current of 30 mA flows
With 1.5 V applied across terminals CD a current of 15 mA flows
a) Write down four equations relating the potential difference, the resistor values and the
currents.
b) Determine the value of resistor R5.
c) If the ends C and D are connected together, what would be the resistance measured between
A and B?
d) If the length AC (and also BD) is 60 metres of resistive wire, how far from A (or C) does the
fault occur?
2. Homework Equations
The Attempt at a Solution
I was able to do all the questions up to part d after which I just blanked. I don't know where or how to approach this question and I'm not sure if it is a gap in my knowledge. Please help!
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