A solenoid is a coil of wire. Despite
being something so simple, solenoids have
many useful applications. They are used
in the natural magnets, electromagnetic
locks, and many other areas. Solenoids
generate a magnetic field when a current
is run through it. The magnetic field
they generate is what makes them so
useful. We analyse the magnetic field
around a loop by looking at the magnetic
field due to each part of the loop and
then adding them together to get the
overall magnetic field. We can do the
same to get the magnetic field of a
solenoid. We know the magnetic root of a
loop now, so we don't need to split the
solenoid into many small sections.
Instead we could split the solenoid into
multiple loops and consider the overall
magnetic field. Let's say we had a
current going in to the right, and out to
the left. Then each individual loop has a
current going down in front and up
behind. Each loop would have a magnetic
field going to the right inside the loop,
and go into the left outside the loop.
Since all these magnetic fields point in
the same direction, they all reinforce
each other, meaning the overall magnetic
field of the solenoid will be pointing
to the right in the middle of the
solenoid, and to the left outside of the
solenoid. The magnetic field around a
solenoid is the same as the magnetic
field around a bar magnet. The difference
is in how they are generated. A bar
magnet has a permanent magnetic field.
While you can switch the magnetic field
around a solenoid on and off by
switching the current on and off. This
has many practical applications.
Electromagnets is one such application.
and electromagnets is exactly as its
name describes. A magnet that is created
by electricity. It's basically a solenoid.
When you run a current through it, it
acts like a magnet. When you turn off the
current, it loses its magnetic field and
stops acting like a magnet. These are
used in electromagnetic locks. There is
generally an armature plate that the
electromagnet is attracted to once a
current is run through it.
