Energy & Electricity in Science : How Does a Solenoid Work?

Hi, I'm Steve Jones and I'm going to tell
you how a solenoid works.

Well first of all, what is a solenoid?

It's very simple, it is a coil of wire.
This is usually copper wire

This is usually copper wire and
as you can see here, it's coiled around like this,

around some kind of former, this may be cardboard,

it may be some other material,
maybe plastic.

Now the solenoid works because an electric current as you can see,

an electric current indicated by these red arrows,

flows through the wire that's provided
by a power supply and a switch.

So we can switch this electric on and off.

This electric current creates a magnetic field.

And in fact,

this solenoid when it's switched on becomes a magnet.

The solenoid,

the word solenoid means just this coil of wire,

but it becomes a magnet
when the current is switched on.

When it's switched off, it stops being magnetic.

The more the current, the greater the current,
the more powerful the magnet.

Now for example:
in a car starter motor, there is a solenoid

and as soon as the electricity passes through
it,

it connects a device which connects
the starter motor and turns the engine.

These solenoids are used everywhere,

particularly in houses for cutting off
the current, if the current is too great.

So, if the current gets too big, the solenoid
becomes a much more powerful magnet.

Here, piece of iron and a spring and,
the iron is connected to the main circuit.

So we've got a circuit out here

and the main circuit is here and
you can imagine that

if this solenoid becomes very strong,
a strong magnet,

this iron will move away from this
which is a solid fixed connection.

That will break this circuit and that is called
a circuit breaker.

So, a solenoid is a very simple device,
a coil of wire,

but it has many, many uses and nowadays,
you will find solenoids everywhere.

Everywhere in your washing machine
and in your home.