Can someone help me to answer the following?

(b) The circuit shown in Figure 1 can be used to measure the resistance of a platinum resistance thermometer (PRT). AB is a uniform resistance wire of length 1.0 m and C is a sliding contact on this wire. A standard resistor R is included in the circuit. The position of C is adjusted until the voltmeter V reads zero.

(i) By applying Kirchhoff’s laws to loops ADCA and BCDB, deduce an expression for the resistance of the PRT in terms of l1, l and the value of the standard resistor.

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I have tried a few times and ended up with an expression PRT=R*l1/(L-l1). But im worried I am not using the loop rule correctly.

Im sorry you cannot see the circuit as I cant post links to this on here.

Thank you for any help.

1 answer

I have no idea of the circuit.