Hi -

I'm pretty confident in my answer to the question below, but would be grateful if it could be double-checked against expert opinion please ?

Many Thanks

(a) 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 1.00m 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. A B D PRT R Figure 1 For use in question 4. (i) By applying Kirchhoff's laws to loops ADCA and BCDB, deduce an expression for the resistance of the PRT in terms of 1, I and the value of the standard resistor. (ii) The PRT consists of 9.00 m of wire of diameter 8.4 x 10-2 mm. The voltmeter reads 0 V when /1 = 0.422 m. If the standard resistor, R, has a resistance of 220?, what is the resistivity of platinum? Show that you have checked that the value for the resistivity and its unit are sensible. (b) Indicate briefly what factors might affect the precision of the measurement when using such a simple circuit to measure the resistance of the PRT