Magnetism And Electromagnetism

Question 1

Permanent magnets

Answer 1

Attracts other magnetic materials. They can not be switched off (permanent)

Question 2

Naturally magnetic materials

Answer 2

Nickel
Iron
Cobalt

Question 3

Making magnets - Soft

Answer 3

• Easy to make into magnet

* Easy to loose magnetism

Question 4

Making magnets - Hard

Answer 4

• Difficult to make into magnet

* It becomes a permanent magnet

Question 5

Magnetic field lines

Answer 5

• like poles repel
• Unlike poles attract
• magnetic field lines point away North, towards South

Question 6

Iron filings - SHAPE

Answer 6

• get magnet
• put paper on top
• sprinkle iron filings while tapping paper
• iron will line up according to shape

Question 7

Iron filings - DIRECTION

Answer 7

• Paper down
• magnet on top
• plotting compass close to magnet
• where arrow points to magnet you draw a line

Question 8

Electromagnetism

Answer 8

• When current flows, conventional current flows in wire, it gets hot and a magnetic field appears
• This happens even to non-magnetic materials

Question 9

Right hand grip rule

Answer 9

• Thumb points in direction of current flow

* fingers points in direction of magnetic field

Question 10

The motor effect

Answer 10

• When a current flows in a wire, a magnetic field is induced
• This magnetic field interacts with the magnetic field of the permanent magnet
• The wire experiences a force and is pushed or pulled in

Question 11

How can we change the direction of motion?

Answer 11

• Reserve the direction of the current flow

* Reserve the direction of the magnetic field

Question 12

How the motor effect works

Answer 12

• the wire is wound around an armature
• a spindle through the armature allows it to rotate
• one side of the armature is pushed up while the other is pushed down
• the direction of the current flowing through the wire must be reversed every half turn using a split ring commutator
• the carbon brushes against the copper when the commutator spins

Question 13

How to make a magnet

Answer 13

• coil of wire to make electromagnet
• stroke on magnetic material
• place it on permanent magnet

Question 14

how to destroy a magnet

Answer 14

By dropping them (vibrations)
Hearing them (vibrations)
A coil with alternating current can demagnetise it

Question 15

the loudspeaker

Answer 15

• An AC Current (changing current) is needed for the speaker to function
• A current will flow in the coil and this produces a magnetic field around the coil
• the changing magnetic field will interact with field of the permanent magnet