gcsescience.com                                       27                                       gcsescience.com


What is a Diode?

A diode is a component that will allow electricity to
pass through it in one direction only.
The circuit symbol is like an arrow pointing to a bar.

Direction of Current flow in a Diode

Electricity can only pass in the direction in which
the arrow points. The diode has
a very big resistance in the reverse direction.

A graph of current against voltage for a diode is
shown below. The plot is not a straight line
showing that a diode does not obey ohm's law.

Plot of Current against Voltage for a Diode

The graph does not go through the origin because
a small voltage is needed before a diode starts
to conduct electricity and allow a current to flow.

What is a
Diode used for?

A diode can be used to protect electrical equipment
from damage if a battery is connected
with the incorrect polarity (the wrong way round).

The LED is a type of diode that emits light.

Diodes can be used in circuits with alternating current.

Back        Links        Electricity        Revision Questions        Next

gcsescience.com        Physics Quiz        Index        Electricity Quiz        gcsescience.com

Home      GCSE Chemistry      GCSE Physics

Copyright © 2015 gcsescience.com. All Rights Reserved.