IV Graph

Key Stage 4

Meaning

An IV graph is a graph showing how the current (I) through a component changes with the potential difference (V) across component.

On an IV graph the potential difference is plotted on the x-axis and the current is plotted on the y-axis.
An IV graph can be used to identify the characteristics of an unknown electrical component. This may be useful when inventing new components.
The resistance of an component can change with the current or the potential difference.
The resistance of a component can be found by taking the ratio of potential difference to current at a point on the curve of an IV graph.

Examples

 The IV graph for a resistor shows that current is directly proportional to potential difference. The IV graph for a bulb shows that as the potential difference increases the current increases. However, at large potential differences a change in potential difference causes a smaller increase in current for a change at small potential differences. The IV graph for a diode shows that for a positive potential difference the current increases rapidly with an increase in potential difference while for a negative potential difference the current remains negligible and does not increase as the potential difference becomes larger. The IV graph for a light dependent resistor shows that at a high light intensity the current increases rapidly with the potential difference whereas at a low light intensity the current increases slowly with the potential difference.

References

Edexcel

I-V graphs, page 187, GCSE Combined Science; The Revision Guide, CGP, Edexcel
I-V graphs, page 74, GCSE Physics; The Revision Guide, CGP, Edexcel
I-V graphs, pages 227-229, GCSE Physics, CGP, Edexcel
I-V graphs; diodes, page 229, GCSE Physics, CGP, Edexcel
I-V graphs; filament lamps, page 228, GCSE Physics, CGP, Edexcel
I-V graphs; fixed resistors, page 228, GCSE Physics, CGP, Edexcel
I-V graphs; LDRs, page 229, GCSE Physics, CGP, Edexcel
I-V graphs; thermistors, page 229, GCSE Physics, CGP, Edexcel

OCR

I-V graphs, pages 45-47, Gateway GCSE Physics; The Revision Guide, CGP, OCR