P15 (Magnetism)

Question 1

Properties of magnets

Answer 1

• two poles, north and south
• produce magnetic field
• non contact force

Question 2

2 Types of forces in a magnet

Answer 2

• attraction

- repulsion

Question 3

How does a compass work?

Answer 3

• tiny bar magnet
• north pole attracted to south pole of any other near magnet
• points in the direction the magnetic field is in

Question 4

Permanent magnet

Answer 4

• produce their own magnetic field

Question 5

Induced Magnet

Answer 5

• magnetic material that turns into a magnet inside a magnetic field

Question 6

The right- hand rule

Answer 6

• do the ‘thumbs up’

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

Question 7

What determines the strength of a magnetic field

Answer 7

• larger current

- closer to the wire

Question 8

Solenoid + increase strength

Answer 8

• coil of wire

- increase strength by wrapping more wires into a coil

Question 9

What is an electromagnet?

Answer 9

• solenoid with an iron core (where magnetic field can be turned on and off through a current)

Question 10

2 Uses of Electromagnets

Answer 10

• used for scrap yards pick up metals

- used within other circuits to act as switches

Question 11

Motor effect

Answer 11

• current carrying wire is put between magnetic poles
  – the magnetic field around the wire interacts with the magnetic field it has been placed in
  – magnet on the conductor exert a force on each other so the wire moves

Question 12

Describe the interaction between the magnetic field and the direction of current (motor effect)

Answer 12

The force acts at right angles to the magnetic field of the magnets and the direction of the current

Question 13

Fleming’s left-hand rule

Answer 13

– First finger is the direction of the field
– second finger (to the rights) direction of the currents
- thumb is the motion (force)

Question 14

How loud speakers work

Answer 14

– And AC current is sent for a coil of the wire
– the coil surrounds one poll of a permanent magnet and is surrounded by another pole so a current causes of force on a coil (cone moves)
- variation in current makes the cone vibrate
- pressure causes sound waves

Question 15

The generator effect

Answer 15

– The induction of a potential difference in a wire is moving relative to a magnetic field, or experiencing a change in magnetic field

Question 16

Alternators

Answer 16

– Generate alternating-current
– rotate a coil in a magnetic field
- as the coil spins a current is induced in the coil, the current changes direction every half turn

Question 17

Dynamos

Answer 17

This swap is the connection every half turn to keep the current flowing in the same direction

Question 18

Transformers

Answer 18

– They change the size of the potential difference of an alternating-current
– two coils (primary and secondary) joined with an iron core

Question 19

Step up transformers

Answer 19

– Step the potential difference up, they have more turns on the secondary coil

Question 20

Get down Transformers

Answer 20

Step the potential difference down, they have more turns on the primary coil