magnetism

Question 1

What are the properties of a magnet?

Answer 1

• magnets have two poles (north and south)
• like poles repel, opposite poles attract
• magnets attract magnetic materials, and magnetic materials are attracted to magnets when unmagnetized
• magnetically hard materials, like steel, retain their magnetism once magnetized
• magnetically soft materials, like soft iron, lose their magnetism when they are no longer exposed to a magnetic field
• magnetic fields go from north to south

Question 2

What is an electromagnet?

Answer 2

Electromagnets are made of a coil of wire wrapped around a magnetically soft core and can be turned on and off

Question 3

What is induced magnetism?

Answer 3

The temporary process of turning a material into a magnet by placing it in a magnetic field

Question 4

What are some methods of magnetisation?

Answer 4

Stroking - stroking a magnetic material with a permanent magnet can induce magnetism

Using a direct current - passing current through a solenoid can magnetize the metal core
Induced magnetism - placing a magnetic material within the field of a strong permanent magnet

Question 5

Describe an experiment to identify the pattern of field lines around a bar magnet.

Answer 5

Observe the direction in which the compass needle points at various points around the magnet. Draw a short line in the direction of the needle at each point. Repeat the process by moving the compass to different locations around the magnet. Join the lines together to reveal the path of the magnetic field lines.

Question 6

Distinguish between the magnetic properties of iron and steel

Answer 6

• Iron is easier to magnetize than steel
• Steel retains magnetism longer than iron
• Iron is used to make electromagnets, while steel is used to make permanent magnets

Question 7

Distinguish between the design and uses of permanent magnets and electromagnets.

Answer 7

Permanent magnets are solid materials that are permanently magnetized. Electromagnets are made from a coil of wire that generates a magnetic field when an electric current passes through it

Permanent magnets are used in applications such as fridge magnets and magnetic strips. Electromagnets are used in applications such as relays, switches, and lifting magnets.