A student investigates how the resistance of a small coil of wire changes with the potential difference (voltage) across it. The student is provided with a DC power supply, an ammeter, a voltmeter, a variable resistor, and the coil of wire.
State how the ammeter and the voltmeter should be connected in the circuit relative to the coil of wire.
Describe how the student should use the variable resistor to obtain a range of current and voltage readings.
Suggest why it is important to keep the temperature of the coil of wire constant during this experiment.
Describe one practical method the student could use to keep the temperature of the coil constant.
State the relationship linking potential difference (voltage), current, and resistance.
Since the temperature remains constant, the coil behaves as an ohmic conductor. Describe the shape of the graph if the student plots resistance on the vertical axis against voltage on the horizontal axis.
25 exam-style questions on Edexcel IGCSE Physics Energy and voltage in circuits. Each one has a worked solution and a mark scheme showing where the marks go.