A student constructs a simple circuit by connecting an adjustable dc power source across an unknown resistor Rx in series with a precision ammeter. By varying the source setting, the student obtains the following pairs of current I and corresponding potential difference across the resistor ΔVx.
I (mA): 35, 50, 60, 80
ΔVx (V): 4.2, 6.0, 7.3, 9.7
(a) Using the data above, derive an experimental value for the resistance Rx. Clearly outline how you process the data to minimize random error.
(b) The student next connects a second resistor R0=120Ω in series with Rx and maintains a constant supply voltage of 12 V. Calculate the current now flowing through the circuit.
(c) Determine the potential difference across each resistor in the series combination from part (b).
(d) Explain how the results of parts (b) and (c) could be used to check the internal consistency of the measured value of Rx obtained in part (a).