SP8a Magnets and magnetic fields

Question 1

How do magnets affect each other?

Answer 1

.like magnets repel each other
.opposite magnets attract

Question 2

What are 3 magnetic materials?

Answer 2

.cobalt
.iron
.nickel

Question 3

What is the difference between permanent and induced magnets? (their magnetism)

Answer 3

.permanent magnets can produce their own magnetic field and retain their magnetism for many years
.induced magnets are magnetised and demagnetised

Question 4

How can magnets be magnetised?

Answer 4

.by stroking with a magnet
.using a direct current coil

Question 5

How can induced magnets be demagnetised?

Answer 5

.by dropping
.by heating
.by putting into an alternating circuit

Question 6

What can permanent magnets do to soft magnetic materials?

Answer 6

make them into induced magnets.

Question 7

What can induced magnets not do?

Answer 7

repel, they can only attract.

Question 8

What are 4 general uses permanent magnets?

Answer 8

.electronics
.motors and generators
.MRI machines
.consumer goods (toys, fridge magnets)

Question 9

What are 4 general uses of temporary magnets?

Answer 9

.electromagnets (junkyard magnetic cranes for ex)
.switches and relays
.MRI machines
.levitation trains

Question 10

Describe the functions of permanent and temporary magnets in MRI machines.

Answer 10

.permanent magnets are used as they produce strong and stable magnetic fields essential for imaging
.temporary magnets are used to fine-tune magnetic fields during imaging procedures

Question 11

What do two flat magnets form?

Answer 11

a uniform magnetic filed, with the same strength and direction everywhere.

Question 12

Describe the magnetic field in a horseshoe magnet.

Answer 12

the poles are closer together meaning there is a stronger field across the end of the magnet.

Question 13

How can the shape of a magnetic field be shown using a plotting compass?

Answer 13

by placing the compasses at various points around a magnet, we can trace out the magnetic field lines.

Question 14

How do magnetic compasses give evidence for the Earth’s magnetic core?

Answer 14

.the magnetic field around the Earth is similar in shape to that of a bar magnet, caused by electric currents in the molten outer iron core
.compasses provide evidence that the Earth’s core must be magnetic, because the needle aligns itself with that field.