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Electricity

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.

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.

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.

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