A 15V power supply of negligible internal resistance is connected to a 30Ω resistor. A practical voltmeter of resistance 10kΩ is available for measuring the potential difference across the resistor.
(a) With the instruments connected correctly, calculate (i) the current in the circuit and (ii) the reading on the voltmeter.
(b) The voltmeter is accidentally connected in series with the resistor while the ammeter remains correctly placed. Determine (i) the current that now flows in the circuit and (ii) the reading shown by the voltmeter.
(c) Compute the percentage error introduced in the current measurement because of the mis-connection in part (b). Comment on why such an error is unacceptable in an electrical measurement.