Topic 10 - Electromagnetic Induction and Magnets

Question 1

permanent magnet

Answer 1

a magnet that is always magnetic, such as a bar magnet

Question 2

magnetic field

Answer 2

Space around a magnet where it can attract magnetic materials

Question 3

induced magnet

Answer 3

When a piece of magnetic materials is in a magnetic field it becomes a magnetic self

Question 4

how can the shape of a magnetic field be found?

Answer 4

using a plotting compass

Question 5

which ways do the lines in a magnetic field flow from

Answer 5

North to south

Question 6

when is a magnetic field strongest

Answer 6

when the lines are closest together (closest to the poles)

Question 7

How is the earths magnetic field caused

Answer 7

by electric currents in the molten outer core

Question 8

How does the strength of the magnetic field depend on the size of the current?

Answer 8

The higher the current the stronger the field

Question 9

electromagnet

Answer 9

A coil of wire with a current flowing through it

Question 10

When is the magnetic field strongest around an electromagnet

Answer 10

It’s stronger closer to the wire and gets weaker with increasing distance

Question 11

what is the magnetic field like around a wire

Answer 11

it’s in multiple circles around the wire
-> strength of magnetic field depends on size of current
-> if current changes direction so does the direction; of magnetic field

Question 12

solenoid

Answer 12

a wire made into a coil

Question 13

what is the magnetic field of à solenoid like outside and inside the solenoid

Answer 13

The magnetic field from all the different parts of the wire form an overall magnetic field like the one around the bar magnet
-> the fields from individual coils add together to form a very strong field inside the solenoid
-> outside the solenoid the fields from one side of the coil tend to cancel out the fields from the other side to give a weaker field outside

Question 14

how can the magnetic field of an electromagnet be made stronger?

Answer 14

• putting a piece of iron inside the coil -> this iron becomes a temporary magnet (it is only magnetic when the field from the electromagnet is affecting it)
• more coils of the wire

Question 15

motor effect

Answer 15

When a force is exerted between a magnetic field and a current-carrying conductor placed in that field

Question 16

What magnetic fields are produced when a wire is placed between two magnets? (Force)

Answer 16

The wire carrying a current experience as a force when it’s place between the two magnets the current in the wire create a magnetic field around the wire and interact with the magnetic field between the magnets. The force is greatest when the wire is at right angles to the magnetic field produced by the magnet and when the wire is in the same direction as this magnetic field.

Question 17

What is Flemming’s left-hand rule?

Answer 17

It shows how the directions of the force magnetic field and current are related when a wire is placed in between two magnets

Question 18

What’s the equation for the force conductor carrying carbonate right angle to magnetic field?

Answer 18

Magnetic field strength (magnetic flux density) x current x length

Question 19

An electric motor to rotate

Answer 19

The force on a conductor in a magnetic field is used to cause rotation in electric motors

Question 20

What are ways to increase the total force turning the coil? (ELECTRIC MOTOR)

Answer 20

Using a coil with many turns of wire

Question 21

Split ring commutator

Answer 21

Part of an electric motor which ensures that the force on the coil always turns it in the same direction

Question 22

When can a voltage or potential difference be induced (electromagnetic induction).

Answer 22

• when the wire experiences a change in the magnetic field
• If a wire is moved into a magnetic field
  -> this induced p.d. causes a current to flow -> only happens of ends of wire connect (close circuit)

Question 23

size of induced p.d. depends on…

Answer 23

• number of turns in a coil of wire
• strength of the magnetic field
• how fast the magnetic field changes or moves past the coil

Question 24

What happens if you reverse the direction of the magnetic field change?

Answer 24

It reverses the direction of the induced potential difference

Question 25

generator

Answer 25

A device that transforms mechanical energy into electrical energy typically by electromagnetic induction and it consists of a coil of water that is rotated inside a magnetic

Question 26

Function of carbon brushes in a alternator

Answer 26

Create electrical contact with an external circuit
- They press on the slip rings

Question 27

Function of slip ring commutator in an alternator

Answer 27

Ends of the coil air connected to slip rings

Question 28

alternator

Answer 28

Name given to generators that produce an alternating current