Magnetism and Electrmagnetism

Question 1

what are the two poles of a magnet

Answer 1

north and south

Question 2

what is a magnetic field

Answer 2

a region where other magnets or magnetic materials experience a force (non contact force)

Question 3

the closer together the magnetic feild lines are………

Answer 3

the stronger magnetic feild

Question 4

the further away the magnetic field lines are……

Answer 4

the weaker the field is

Question 5

where is the magnetic field strongest?

Answer 5

at the poles of the magnet

Question 6

where is the magnetic force the strongest?

Answer 6

at the poles

Question 7

the force between a magnet and a magnetic material is always….

Answer 7

attractive

Question 8

two poles which are the same

Answer 8

repel

Question 9

two opposite poles will

Answer 9

attract

Question 10

what do compasses show

Answer 10

the direction of magnetic feilds

Question 11

when compasses are not near a magnet the needle always points

Answer 11

north

Question 12

what are the two types of magnets

Answer 12

permanent and induced

Question 13

what type of magnet produces its own magnetic field

Answer 13

permanent magnetic

Question 14

what type of magnet is a magnetic material that turns into a magnet when they are put into a magnetic field

Answer 14

induced magnet

Question 15

what happens to an induced magnet when you take away the magnetic field

Answer 15

induced magnets quickly lose most or all of their magnetism

Question 16

the larger the current through the wire, or the closer to the wire you are

Answer 16

the stronger the field is

Question 17

what is the field made up of

Answer 17

concentric circles perpendicular to the wire

Question 18

how to work out which way the direction of the magnetic field if the current changes

Answer 18

right hand thumb rule

Question 19

how do you increase the strength of the magnetic field that a wire produces?

Answer 19

wrapping the wire into a coil called a soleniod

Question 20

why is the magnetic field stronger, with a solenoid?

Answer 20

the field lines around each loop of wire line up with each other, this result in lots of field lines pointing in the same direction that are very close to each other, this mean the magnetic field is stronger

Question 21

what is the magnetic field like inside a solenoid

Answer 21

strong and uniform

Question 22

how can you increase the magnetic field of the solenoid even more?

Answer 22

putting a block of iron in the centre of the coil. this iron core becomes an induced magnet whenever the current is flowing

Question 23

if you stop the current

Answer 23

the magnetic field stops

Question 24

what is a solenoid with an iron core called

Answer 24

an electromagnet

Question 25

what is an electromagnet

Answer 25

a magnet whose magnetic field can be turned on and off with an electric current

Question 26

what happens when a current caring wire (or any other conductor) is put between magnetic poles

Answer 26

the magnetic field around the wire interacts with the magnetic field is has been placed in. this causes the magnet and the conductor to exert a force on each other. this is called the motor effect and can cause the wire to move

Question 27

the force allay acts at ______________ to the magnetic field of the magnets and to the direction of the current in the wire

Answer 27

right angles

Question 28

what is the motor effect used for

Answer 28

in lots of appliances that use movement

Question 29

the force increase with the amount of ____________________ passing through the conductor

Answer 29

current

Question 30

what is a good way of showing the direction of the force

Answer 30

apply a current to a set of rails inside a horseshoe magnet. a bar is placed on the rails, which completes the circuit. this generates a force the rolls the bar along the rails

Question 31

equation for magnetic flux density

Answer 31

F = Bl L

Question 32

how to find out which direction the force is going

Answer 32

Flemings left hand rule

Question 33

flemmings left hand rule;

Answer 33

thuMb = motion
First Finger = field
seCond finger = Current

Question 34

what does flemmings left hand rule show

Answer 34

if either the current or the magnetic field is reversed, then the direction of the force will also be reversed

Question 35

a current carrying coil of wire rotates in a magnetic field

Answer 35

forces act of the two sides of a coil of wire that is carrying a current

these forces act in any current in a magnetic field

because the coil is on a axle and the forces act one up and one down, it rotates

Question 36

what does the split ring communicator do

Answer 36

swaps the contacts every half turn to keep the motor rotating in the same direction

Question 37

how can the direction of the wire be reversed?

Answer 37

by swapping the polarity of the dc supply (reversing the current) or swapping the magnetic poles over (reversing the field)

Question 38

what is the motor effect use for examples?

Answer 38

food mixers, DVD players, anything that has a fan ,hairdryers, laptops (electric motor keep things turning)