Energy and Voltage in Circuits

4 marks · Normal

Describe an experiment you could do to find the relationship between current and voltage for a resistor. Your answer should include:

- A description or diagram of the circuit you would use - How you would take your measurements - What you would record - How you would use the data to determine the relationship

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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Must show: Circuit description/diagram with power supply, resistor, ammeter in series, voltmeter in parallel, Change voltage or use variable resistor, Measure current and voltage pairs, Plot I vs V and look for direct proportionality

Common mistakes: Incorrect circuit; Not measuring both quantities; Not plotting graph

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Describes or draws correct circuit (power supply, resistor, ammeter in series, voltmeter in parallel).

M2 · 1 mark · Explains to vary the voltage or use a variable resistor to produce multiple readings.

M3 · 1 mark · States to record pairs of current and voltage or tabulate the results.

A1 · 1 mark · Describes plotting a graph of current against voltage and comments on the relationship.

Worked solution

Set up a circuit with a resistor, power supply, an ammeter in series to measure current, a voltmeter in parallel to measure voltage. Vary the voltage using the power supply or a variable resistor. Record several pairs of current and voltage readings. Plot current (I) against voltage (V) on a graph to see if the relationship is linear (shows I ∝ V).