A student wants to verify Ohm’s law for a nichrome wire of about 10Ω at room temperature.
(i) Draw a neat, labelled circuit diagram of the experimental set-up that the student should use.
(ii) Describe the step-by-step procedure the student must follow to record the potential difference across the wire and the current through it for at least five different settings of the rheostat.
(iii) Explain why the key should be kept open between successive readings and why the rheostat setting should be altered gradually.
(iv) State how the student should use the recorded observations to establish that the wire obeys Ohm’s law.