Top 7 - Magnetism and Electromagnetism

Question 1

What is a magnetic field?

Answer 1

A magnetic field is a region where other magnetic materials experience a force.

Question 2

Give 3 magnetic materials

Answer 2

Iron, Steel, Nickel

Question 3

In what direction do magnetic field lines point?

Answer 3

They go from north to south

Question 4

What happens to an induced magnet when it is moved far away from a permanent magnet?

Answer 4

It quickly loses its magnetism.

Question 5

Describe the magnetic field around a current-carrying wire.

Answer 5

The field is perpendicular to the current and made up of concentric circles, with the wire in the circle.

Question 6

Give two advantages of a electromagnet compared to a permeant magnet with a crane.

Answer 6

Electromagnets can be turned on and off, good for dropping off materials, permeant magnets can not be.

You can alternate the strength of the magnet by turning the current up and down with an electromagnet this is not possible with a permeant magnet.

Question 7

Why does adding more coils to a solenoid increase the strength of the surrounding field?

Answer 7

It increases the strength because the field lines around each loop of wire line up with each other and this is more frequent the more coils are added.

Question 8

Explain why a current-carrying conductor in a magnet field experiences a force.

Answer 8

When a current-carrying wire (or any other conductor) is put between magnetic poles, the magnetic field around the wire interacts with the magnetic field is has been put in.

Question 9

State the equation for calculating the size of this force.

Answer 9

Force (N) = Magnetic Flux Density (T, Tesla) x Current (A) x Length (m)

Question 10

Make the hand signal for Fleming’s left hand rule

Answer 10

Thumb = Motion
First Finger = Field (north to south)
Second Finger = Current

Question 11

Explain how a basic d.c motor works

Answer 11

Forces act upon the two sides of the wire.