7.1. Eletromagnetism - magnetism and basic electromagnetism

Question 1

what are the two poles on a magnet

Answer 1

North Pole and South Pole

Question 2

what do all magnets produce

Answer 2

magnetic field

Question 3

what is a magnetic field

Answer 3

A region where other magnets or magnetic materials experience a force

Question 4

what metals are magnetic

Answer 4

iron
steel
nickel
cobalt

Question 5

How can you show a magnetic field?

Answer 5

By drawing magnetic field lines

Question 6

what way do magnetic field lines always go

Answer 6

from north to south, and 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 the space between magnetic field lines show

Answer 7

the closer together the lines are, the stronger the magnetic field
the further away from a magnet you get, the weaker the field is

Question 8

where is the magnetic field strongest

Answer 8

At the poles of the magnet - the magnetic forces are also strongest at the poles

Question 9

what is the force between a magnet and a magnetic material always

Answer 9

the force between a magnet and a magnetic material is always attractive, no matter the pole

Question 10

What happens when two poles of a magnet are put near each other?

Answer 10

they will each exert a force on each other. this force can be attractive or repulsive. two like poles will repel. two unlike poles will attract

Question 11

how do compasses show the directions of magnetic fields

Answer 11

inside a compass is a tiny bar magnet. the North Pole of this magnet is attracted to the South Pole of any other magnet it is near. so the compass points in the direction of the magnetic field it is in

Question 12

how to use a compass to draw magnetic field lines

Answer 12

you can move a compass around a magnet and trace its position on some paper to build up a picture of what the magnetic field looks like

Question 13

why do compasses always point north

Answer 13

when they’re not near a magnet, compasses always point north because the Earth generates its own magnetic field which shows the core of the Earth must be magnetic

Question 14

what are the two types of magnet

Answer 14

Permanent magnet & induced magnet

Question 15

what are permanent magnets

Answer 15

magnets that produce their own magnetic field

Question 16

what are induced magnets

Answer 16

magnetic materials that turn into a magnet (produce their own magnetic field) when they’re put into another magnetic field

Question 17

what happens to induced magnets when you take away the magnetic field

Answer 17

induced magnets quickly lose their magnetism and stop producing a magnetic field

Question 18

what happens when a current flows through a wire

Answer 18

A magnetic field is created around the wire.
the field is made up of concentric circles perpendicular to the wire, with the wire in the centre

Question 19

what is the right-hand thumb rule

Answer 19

Using your right hand, point your thumb in the direction of current and curl your fingers. The direction of your fingers is the direction of the magnetic field

Question 20

how does the strength of the magnetic field produced by a current change

Answer 20

the larger the current through the wire, or the closer to the wire you are, the stronger the field is

Question 21

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

Answer 21

-increase current through the wire
-get closer to the wire
-wrap the wire into a coil called a solenoid

Question 22

what is a solenoid

Answer 22

A coil of current-carrying wire that produces a magnetic field

Question 23

how can a solenoid have a stronger magnetic field in comparison to a normal wire

Answer 23

because in a solenoid the field lines around each loop of wire line up with each other.
this results in lots of field lines pointing in the same direction that are very close to each other. the closer together field lines are, the stronger the field is

Question 24

how to describe the magnetic field inside a solenoid

Answer 24

strong and uniform (has the same strength and direction at every point in that region)

Question 25

outside the solenoid, what is the magnetic field like

Answer 25

just like the one round a bar magnet

Question 26

how can you increase the field strength of the solenoid even more

Answer 26

by putting a block of iron in the centre of the coil. this iron core becomes an induced magnet whenever current is flowing, and creates its own magnetic field. the total magnetic field is the magentic field created by the solenoid, plus the magnetic field created by the iron core.

Question 27

what happens when you stop the current of a solenoid

Answer 27

the magnetic field disappears

Question 28

what is a solenoid with an iron core called

Answer 28

an electromagnet - because its magnetic field can be turned on and off with an electric current

Question 29

what are electromagnets used for

Answer 29

- used in cranes to attract and pick up things made from magnetic materials like iron and steel (on when want to pick up, off when want to drop it) - used within other circuits to act as switches. when the electromagnet is turned on it attracts the iron contact on the rocker. the rocker then pivots and closes the contacts on the new circuit turning on the motor.

Question 30

why are electromagnets so useful

Answer 30

-they're so quick to turn on and off -they can create a varying force