A student wishes to measure the current through and the potential difference across a resistor using an ammeter and a voltmeter.
(i) Explain, with reasons, how the internal resistances of an ideal ammeter and an ideal voltmeter should compare with the resistance of the circuit element across which they are connected.
(ii) Predict what would happen to the circuit and to the reading of the meter if an ideal ammeter were accidentally connected directly across a resistor instead of in series with it.
(iii) In a circuit powered by a 5V source of negligible internal resistance, a real ammeter of internal resistance 0.5Ω is mistakenly connected in parallel across a 10Ω resistor. Calculate the current that will flow through the ammeter and through the resistor. Comment on the practical consequences of this mistaken connection.