Physics 1.9 Electromagnetism

At which part of a magnet are the magnetic forces strongest?

The poles of the magnet.

What happens when two magnets are brought close to each other?

They exert a force on each other.

What type of force is exerted if two like poles of a magnet are brought near each other?

A repulsive, non-contact force.

What type of force is exerted if two unlike poles of a magnet are brought near each other?

An attractive, non-contact force.

What is a magnetic field?

The region surrounding a magnet where another magnet or magnetic material experiences a non-contact force.

What is produced when current flows through a conducting wire?

A magnetic field is produced around the wire.

How do you work out the direction of the field around a current-carrying wire?

Using the right-hand grip rule.

What determines the strength of the magnetic field around a current-carrying wire?

The magnitude of the current flowing through the wire.

The coils around the wire.

The distance from the wire.

What is a solenoid?

A coil of wire which, when current passes through, creates a strong magnetic field.

Describe the magnetic field found inside a solenoid.

Strong and uniform.

What is an electromagnet?

A solenoid with an added iron core.

Adding the iron core increases the strength of the magnetic field.

What is the motor effect?

When a force is exerted between a magnetic field and a current-carrying conductor placed in that field.

What rule is used to determine the force experienced due to the motor effect?

Fleming’s Left-Hand Rule.

When using Fleming’s left-hand rule, what does the forefinger represent?

The forefinger points in the direction of the magnetic field.

When using Fleming’s left-hand rule, what does the second finger represent?

The second finger points in the direction of current flow in the conductor.

What factors affect the size of the force on a current-carrying wire in a magnetic field?

The magnitude of the current flowing through the conductor.

The strength of the magnetic field that the conductor is placed in.

If the direction of current in a current-carrying wire placed in a uniform magnetic field is reversed, what happens to the force?

The direction of the force is reversed.

If the strength of the current in a current-carrying wire placed in a uniform magnetic field is increased, what happens to the force?

The strength/magnitude of the force is increased.

What criteria must be met for the equation linking force, magnetic flux density, current, and length to apply?

The conductor must be at right angles to the magnetic field it is placed in.

What is the equation linking force, magnetic flux density, current, and length?

F = B I L

Force (N) = Magnetic field strength (T) × Current (A) × Length (m).

What equation is used to link the voltage and number of turns on the coils of a transformer?