Topic 12 - Magnetism and the motor effect

Question 1

What are the main three magnetic elements and the main magnetic alloy?

Answer 1

Iron, nickel, and cobalt, and steel is the alloy

Question 2

What is the difference between permanent and induced magnets?

Answer 2

Permanent magnets produce their own magnetic field all the time; induced/temporary magnets only produce a field while they’re in another magnetic field

Question 3

What are some uses of magnetic materials?

Answer 3

• Fridge doors
• Maglev trains - use magnetic repulsion to keep trains above track and to propel them along
• MRI machines - use magnetic fields to create images of inside of body without ionising radiation
• Speakers and microphones

Question 4

What direction do magnetic field lines always go in?

Answer 4

From north to south

Question 5

The closer together magnetic field lines are and the closer to the magnet you are, is the field weaker or stronger?

Answer 5

Stronger

Question 6

What does the magnetic field around a bar magnet look like?

Answer 6

Each side of the magnet, field lines go from north to south. At the north pole, lines spread outwards, repelling any other north pole away. At the south pole, lines enter inwards, attracting any north pole in the field. (tinyurl.com/barmagnetpic)