electromagents

What is the direction of conventional current

From the positive end of the cell to the negative

What happens when a current flows through a conducting wire

When a current flows through a conducting wire, a magnetic field is produced around the wire

How can we prove there is a magnetic field around the wire

By using a compass

When the current is turned off, the compass needle lines up with the earths magnetic field

However if we turn the current on then the compass needle deflects

What does the strength of the magnetic field depend on

The size of the current. A larger current produces a stronger magnetic field

Magnetic field is strongest closer to the wire. As we move away the magnetic field weakens.

How can we change the direction of the magnetic field

By changing the direction of the current

What happens if we change the direction of the current

Then we change the direction of the magnetic field

What is a solenoid

A coil of wire

What happens when we use a solenoid and turn on the current

We get a strong and uniform magnetic field inside the solenoid. The magnetic field around a solenoid has a similair shape to the magnetic field of a bar magnet

3 ways to increase the strength of the magnetic field produced by a solenoid

Increase the size of the current

Increase the number of turns of the coil

If we place a piece of iron inside the solenoid, called an iron core

What is an electromagnet

A solenoid containing an iron core

Why are electromagnets useful

We can change the strength of the magnetic field by chanting the size of the current

We can turn an electromagnet on and off

Describe the shape of the magnetic field produced around the straight wire

Concentric circles