I-V Characteristics

This lesson covers the current-voltage (I-V) characteristics of key components, as required by the Edexcel GCSE Combined Science specification (1SC0). You must be able to describe, sketch and interpret I-V graphs for a resistor, filament lamp and diode.

---

What Is an I-V Characteristic?

An I-V characteristic is a graph that shows how the current (I) through a component changes as the potential difference (V) across it changes.

• The x-axis shows potential difference (V).
• The y-axis shows current (I) in amps (A).
• The graph often extends into negative values of V and I to show what happens when the voltage is reversed.

How to Obtain I-V Data

1. Set up the component in a circuit with a variable resistor (or variable power supply), an ammeter in series and a voltmeter in parallel.
2. Start with the lowest voltage and gradually increase it.
3. Record the voltage (V) and current (I) at each setting.
4. Reverse the connections to the battery and repeat for negative voltages.
5. Plot V on the x-axis and I on the y-axis.