Diode

Key Stage 4

The symbol for a diode.

A diode is an electrical component which only allows electricity through in one direction.

Diodes have a low resistance in one direction but a very high resistance in the reverse direction.

The IV Graph for a diode shows that:

For a positive potential difference the current increases rapidly with an increase in potential difference
For a negative potential difference the current remains negligible and does not increase as the potential difference becomes larger.

The resistance of a diode is very low for current in the forward direction and very high in the back direction.

	Connect an ammeter in series with the diode to measure current through the diode. Connect a voltmeter in parallel with the diode to measure the potential difference across it. Use a variable resistor in series with the diode to vary the potential difference across the diode. Start with a potential difference of zero and increase the potential difference by an interval of 0.2V up to 2V. Recording the reading on the voltmeter and ammeter. Reverse the connections on the battery and repeat steps 4 and 5 to find the I-V relationship for negative potential difference and current.