Electro Magnetism

Question 1

What are the two poles

Answer 1

North and South

Question 2

What do all magnets produce

Answer 2

A magnetic field

Question 3

What is a magnetic field

Answer 3

A region where other magnets or magnetic materials experience a force

Question 4

Is magnetism a contact or non-contact force

Answer 4

Non contact

Question 5

What are the 4 magnetic materials

Answer 5

• Iron
• Steel
• Nickel
• Cobalt

Question 6

What do you use to show a magnetic field and how do you show it

Answer 6

• Magnetic field lines
• lines go north to south
• they show which way a force would act on a North Pole if it was put at that point in the field

Question 7

What does it mean if the magnetic field lines are closer together

Answer 7

• the stronger the magnetic field
• (So for when they’re further apart = weaker field)

Question 8

What is the force between a magnet and a magnetic material like

Answer 8

Attractive (always, no matter the pole)

Question 9

like poles will

Answer 9

Repel

Question 10

Unlike poles will

Answer 10

Attract

Question 11

What can a compass show

Answer 11

The direction of Magnetic fields

Question 12

How do compasses show the direction of the Magentic field

Answer 12

• tiny metals needle in compass
• it’s North Pole is attracted to the South Pole of any magnet nearby
• so points in direction of magnetic field

Question 13

Why do compasses point north

Answer 13

• Earth generates its own magnetic field, which shows that the inside (core) of the Earth must be magnetic
• the compass need then points north because of this

Question 14

What are the 2 types of magnets

Answer 14

• permanent
• induced

Question 15

What are permanent magnets

Answer 15

They produce their own magnetic fields

Question 16

What are induced magnets

Answer 16

Magnetic material that turn into a magnet when they’re put into a magnetic field

Question 17

Describe the force between a permanent and induced magnet

Answer 17

Attractive

Question 18

What happen when you take an induced magnet out of a magnetic field

Answer 18

It loses most of its magnetism

Question 19

What creates a magnetic field

Answer 19

• when a current flows through a wire, a magnetic field is created around the wire

Question 20

Describe the magnetic field around a wire

Answer 20

• made up of concentric circles perpendicular to the wire
• with the wire in the centre

Question 21

How do you see the magnetic field around a wire

Answer 21

• place a compass near wire that’s carrying current
• As you move the compass, it’ll trace the direction of the magnetic field

Question 22

How does changing the direction of current in a wire affect the magnetic field around the wire

Answer 22

• changing direction of current = changes direction of magnetic field
• use the hand-thumb rule to work out which way it goes

Question 23

What from the wire affects the strength of the magnetic field

Answer 23

• The strength of the magnetic field changes WITH the current and the distance from the wire
• the larger the current or the closer you are to the wire = the stronger the field is

Question 24

What is a solenoid

Answer 24

A coil of wire

Question 25

How do you increase the strength of a magnetic field produced by a wire

Answer 25

- wrapping the wire into a coil called a solenoid

Question 26

Why does wrapping a wire into a solenoid increase the strength of the magnetic field

Answer 26

- the field lines around each loop of wire line up with each other - resulting in lots of field lines pointing in the same direction that are very close together - and therefore the closer the field lines are = the stronger the field is

Question 27

Describe the magnetic field inside a solenoid

Answer 27

- strong - uniform —> it has the same strength and direction at every point in that region

Question 28

Describe the magnetic field outside a solenoid

Answer 28

Just like that around a bar magnet

Question 29

How can you further increase the field strength of a solenoid even more

Answer 29

- put a block of iron in the centre of the coil - the iron core becomes an induced magnet whenever current is flowing - (But if you stop the current, the magnetic field disappears)

Question 30

What is a solenoid with an iron core called

Answer 30

- electromagnet - (a magnet whose magnetic field can be turned on and off with an electrical current)

Question 31

What happens to a current in a Magnetic field

Answer 31

- it experiences a force

Question 32

Explain the Motor effect

Answer 32

- current carrying wire (conductor) is put between magnetic poles - magnetic field around wire interacts with magnetic field it has been placed into - causing magnet and conductor to exert a force on each other - causing the wire to move

Question 33

How do you make the wire experience the full force of the motor effect

Answer 33

- place it 90’ in a magnetic field - if it’s parallel = no force

Question 34

How does the force act in the motor effect

Answer 34

- at right angles to the magnetic field - and the direction of the current in the wire

Question 35

As the strength increases, what happens to the magnitude of the force

Answer 35

Increases —> it’ll also increase with the amount of current passing through the conductor

Question 36

What does the force acting on a conductor in a magnetic field depend on

Answer 36

- magnetic flux density - size of current through conductor - length of conductor that’s in the magnetic field

Question 37

What is the magnetic flux density

Answer 37

How many field lines there are in a region —> shows strength of a magnetic field

Question 38

How do you find the direction which a force is acting during the motor effect

Answer 38

- Fleming’s left hand rule - thuMb = Motion - First finger - Field - seCond finger = Current

Question 39

What happens to a current-carrying coil of wire in a Magnetic field

Answer 39

It will rotate