A student is investigating the electrical properties of a long piece of ni-chrome wire. The student has access to the following list of apparatus: 30 cm ruler, ammeter, connecting leads, electronic balance, small electric motor, metre rule, 6 V fixed-voltage DC power supply, switch, tape measure, variable resistor (rheostat), voltmeter.
From the list, choose the most suitable device to measure a package of wire that is approximately 15 m long.
Describe how the ammeter, voltmeter, and variable resistor should be connected to the ni-chrome wire in a circuit to measure its current for a range of different potential differences.
The student replaces the ni-chrome wire with a small electric motor. When the circuit is switched on, the motor does not rotate. Suggest how the student can use the existing circuit to check if a current is actually passing through the motor, without removing the motor.
State whether a voltmeter with a range of 0 - 300 V is suitable for measuring the potential difference across the wire in this circuit. Give a reason for your answer.
136 exam-style questions on CIE IGCSE Physics 4.3 Electric circuits, covering 4.3.1a Circuit diagrams and circuit components, 4.3.2a Series circuits, 4.3.2b Parallel circuits, 4.3.2c Current and potential difference in circuits, 4.3.2d Combined resistance of resistors in parallel, and 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.