The active element, Ru in a Wheatstone bridge is a copper resistance temperature detector (RTD) used to measure temperature inside an industrial oven. The copper RTD has a temperature coefficient of 0.0393Ω/Ω/∘C and a nominal resistance of 100Ω at 0∘C. The other bridge resistor arms are fixed at the RTD nominal resistance. The current through the nickel RTD must be limited to 5 mA.

a) Calculate the maximum allowable supply voltage for the bridge circuit. Explain why the current through the RTD has a maximum limit.

b) Determine the change in RTD resistance and the bridge output voltage when the oven temperature is increased to 125∘C. Assume that the voltmeter across the bridge is ideal.

c) The bridge output voltage is measured using a voltmeter with internal resistance of 50kΩ. Determine the actual voltage measured by the non-ideal voltmeter at the same temperature in part (b).