Magnetism

Question 1

What is magnetism?

Answer 1

The ability of magnets to attract and repel other magnets without physical contact

Question 2

What do magnets produce?

Answer 2

Magnetic field

Question 3

What does a magnetic field make other magnets or magnetic materials experience?

Answer 3

A force

Question 4

Why do opposite poles attract when 2 magnets are close?

Answer 4

Magnetic fields overlap

Question 5

What is created when opposite poles are placed near each other?

Answer 5

A uniform field

Question 6

What is a uniform field?

Answer 6

A magnetic field that is the same everywhere between the poles

Question 7

How do you tell if an object is a magnet?

Answer 7

It will attract magnetic materials and repel one pole of another magnet

Question 8

What causes there to be magnetic forces?

Answer 8

Magnets producing magnetic field

Question 9

What are magnetic forces?

Answer 9

Forces between magnets

Question 10

Where is the magnetic field strongest?

Answer 10

Poles

Question 11

Where are the magnetic forces strongest?

Answer 11

Poles

Question 12

What do permanent magnets always produce?

Answer 12

A magnetic field

Question 13

When a magnetic material is in a magnetic field, what does it become?

Answer 13

Induced magnet

Question 14

What do permanent magnets create in magnetic materials?

Answer 14

Temporary poles which align so the magnetic material is attracted to the permanent magnet

Question 15

Why is the force between a magnet and magnetic material always attractive?

Answer 15

Magnetic induction- the South Pole induces a North Pole in the magnetic material and vice versa

Question 16

What are induced magnets?

Answer 16

Magnetic materials that produce a magnetic field in a magnetic field

Question 17

What happens to an induced magnet when a permanent magnet is taken away?

Answer 17

They return to normal and don’t produce a magnetic field

Question 18

What materials quickly use magnetism?

Answer 18

Magnetically soft materials eg iron, nickel and iron alloys

Question 19

What materials slowly use magnetism?

Answer 19

Magnetically hard materials like steel

Question 20

3 main magnetic elements

Answer 20

Iron, nickel, cobalt

Question 21

What are magnetic materials always attracted to if they are within the magnetic field?

Answer 21

A magnetic

Question 22

Are magnetic materials repelled?

Answer 22

No

Question 23

What is inside a plotting compass?

Answer 23

A tiny bar magnet called a needle that lines up with the magnetic field it’s in

Question 24

Why will the needle of a compass point in the direction of the North Pole when not near a magnet?

Answer 24

The earth’s core is magnetic so it generates its own magnetic field

Question 25

What does an electric current produce?

Answer 25

A magnetic field

Question 26

What will a wire have created around it when a current flows through it?

Answer 26

A magnetic field

Question 27

What will the magnetic field lines created in a wire with a current look like?

Answer 27

Concentric circles perpendicular to the wire in the centre

Question 28

What increases the strength of the field in a wire with a current flowing through it?

Answer 28

Larger current and closer to the wire

Question 29

What does changing the direction of the current change?

Answer 29

The direction of the magnetic field

Question 30

To find the direction of the current what rule is used?

Answer 30

Right hand thumb rule

Question 31

What is a solenoid?

Answer 31

A loop of wire coiled into a cylindrical shape that carries an electric current

Question 32

What increases the strength of the magnetic field in a solenoid?

Answer 32

More loops

Question 33

Where is the magnetic field weak in a solenoid?

Answer 33

Outside the solenoid apart from at the ends

Question 34

Where is the magnetic field strong in a solenoid?

Answer 34

Inside

Question 35

What increases magnetic field strength in a solenoid?

Answer 35

Increasing current, putting an iron block in the centre of the coil

Question 36

Why does an iron core increase magnetic field strength in a solenoid?

Answer 36

Becomes an induced magnet when current flows

Question 37

What decreases magnetic field strength of a solenoid?

Answer 37

Increased distance from the solenoid

Question 38

The invention of what has increased the use of magnetic materials?

Answer 38

Electromagnets

Question 39

What is an electromagnet?

Answer 39

A type of magnet in which the magnetic field is produced by an electric current so can be turned on and off

Question 40

3 objects that use electromagnets

Answer 40

Fridge doors, maglev trains, MRI machines

Question 41

What is the motor effect?

Answer 41

When a current-carrying conductor is put between the poles of 2 magnets so the magnetic fields interact and the magnet and conductor experience a force

Question 42

What causes the motor effect?

Answer 42

The magnetic field created by a current interacting with a magnetic field

Question 43

To experience the motor effect what angle must the wire be at to feel the full force?

Answer 43

90 degrees to the magnetic field

Question 44

If the wire runs parallel to the magnetic field, what force will it feel?

Answer 44

None

Question 45

What does the direction of the force on the wire depend on?

Answer 45

The direction of the magnetic field and direction of current flow

Question 46

What rule determines the direction of force of the motor effect?

Answer 46

Fleming’s left hand rule

Question 47

What is Fleming’s left hand rule?

Answer 47

First finger= magnetic field Second finger = current Thumb = force (direction conductor would move)

Question 48

What does the size of the force on a conductor in a magnetic field depend on?

Answer 48

Magnetic flux density, current size and length of conductor

Question 49

What is the magnetic flux density?

Answer 49

Strength of magnetic field

Question 50

What is the force on the wire directly proportional to?

Answer 50

The magnetic flux density, the current and the length

Question 51

When the current is at 90 degrees to the magnetic field, what equation can be used to find the force acting on it?

Answer 51

Force = magnetic flux density x current x length

Question 52

Why does a solenoid rotate on its axis?

Answer 52

Its experiences a force

Question 53

How can the size of the turning force on the solenoid be increased?

Answer 53

Increasing current Increasing magnetic flux density Increasing number of coils

Question 54

What is electromagnetic induction?

Answer 54

The creation of a potential difference and current in a wire experimenting a charge in a magnetic field

Question 55

How can a potential difference be induced?

Answer 55

Moving a conductor Rotating a magnet in a coil of wire Changing magnetic field through an electrical conductor

Question 56

How is a pd induced in transformers?

Answer 56

The magnetic field strength is increased or the charge speed is increased or more turns in a coil of wire

Question 57

What does the induced pd create?

Answer 57

A force which acts in the opposite direction to the action that induced it

Question 58

Why does the induced pd create a force which acts in the opposite direction to the action of that induced it?

Answer 58

Motor effect

Question 59

What direction does the force induced by the motor effect run?

Answer 59

Opposite to the inductive force’s direction

Question 60

What do transformers change?

Answer 60

The potential difference in wires carrying alternating currents

Question 61

How do transformers change pd?

Answer 61

Induction

Question 62

What are transformers made up of?

Answer 62

2 coils- primary and secondary- was hat are joined by an iron core

Question 63

Describe the transformer process

Answer 63

Alternating pd/ current applied to primary coil Alternating current flows through primary coil creating an alternating magnetic field Alternating magnetic field in iron core due to alternating current Alternating magnetic field passes through secondary coil due to alternating current Alternating pd and magnetic field induced in secondary coil

Question 64

How efficient are transformers?

Answer 64

100%

Question 65

Why are transformers 100% efficient?

Answer 65

All energy transferred to the transformer by the primary coil will be transferred to any component connected to the secondary coil

Question 66

What is equal in each coil?

Answer 66

Power

Question 67

Equation for voltage and number of coils in transformers

Answer 67

Voltage primary / voltage secondary = Number primary coils / number secondary coils