Magnetism

Question 1

Define the simple phenomena of magnetism.

Answer 1

Forces between magnets, and between magnets and magnetic materials

Question 2

Name the 3 ferrous metals.

Answer 2

Iron
Nickel
Cobalt

Question 3

Define the law of magnetic poles

Answer 3

Like poles repel, unlike poles attract

Question 4

Describe an experiment to identify the pattern of magnetic field lines, including the direction.

Answer 4

Lay a bar magnet on a sheet of paper
Place the plotting compass at a point near one pole of the magnet
Mark the direction of the compass
Move the compass to follow the magnetic field line
Continue this process until the other pole of the bar magnet is reached

Question 5

Define magnetic field

Answer 5

Region in which a magnetic pole experiences a force
The closer the field lines are to each other the greater the strength of the magnetic field

Question 6

Name 3 ways of magnetisation.

Answer 6

Stroking the material with a magnet
Use direct current in a coil
Hammering in a magnetic field

Question 7

Name 3 ways of demagnetisation.

Answer 7

Hammering
Heating
Using alternating current in a coil

Question 8

Describe hard magnetic materials.

Answer 8

Permanent magnets are made of magnetically hard materials such as steel. These materials retain their magnetisation once magnetised.

Question 9

Describe soft magnetic materials.

Answer 9

Magnetically soft materials, such as iron, lose their magnetisation easily. They suitable for temporary magnets such as electromagnets.

Question 10

Define electromagnet

Answer 10

An electromagnet consists of a current carrying coil wrapped around an iron core. The magnetic effect can be increased by increasing the current; increasing the number of coils or introducing an iron core.

Question 11

Name 4 uses of electromagnets.

Answer 11

Scrap yard crane
Electric bell
Relay switch
Circuit breaker