Voltage & Current Graphs Summary

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Plotting graphs of current (I) against voltage (V) shows how a component behaves.

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For resistance wire (at constant temperature) the resistance is constant, so the graph is a straight line through (0,0):

full current-voltage graph for a wire at constant temperature showing direct proportionality

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For filament lamps, the temperature increases dramatically with increasing current, so the resistance changes and the graph is a curve:

full current-voltage graph for a filament lamp

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For diodes, they only allow current to flow one way through them, so have a zero region for this reverse voltage.

full current-voltage graph for a diode

Diodes also have a strange flat region before they "switch on" allowing current to flow.

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RELATED TOPICS:
Current Electricity | Resistance & Resistors | Ohm's Law


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