P7

Question 1

where are the magnetic forces strongest?

Answer 1

at the poles of a magnet

Question 2

when do magnets exert a force on each other?

Answer 2

when they are close

Question 3

what do permanent magnets produce?

Answer 3

their own magnetic fields

Question 4

what is an induced magnet?

Answer 4

an object that becomes a magnet when it is placed in a magnetic field

Question 5

what does induced magnetism always cause?

Answer 5

a force of attraction

Question 6

what happens to the induced magnet when a permanent magnet is taken away?

Answer 6

loses some or all of its magnetism quickly

Question 7

what are the 4 types of magnetic material?

Answer 7

iron
steel
cobalt
nickel
- can all be made into a permanent or induced magnet

Question 8

what is steel?

Answer 8

an alloy of iron

Question 9

what is a magnetic field?

Answer 9

a region around a magnet where a force acts on another magnet or on a magnetic material

Question 10

what does the strength of the magnetic field depend on?

Answer 10

the distance from the magnet

Question 11

how can the direction of a magnetic field be found?

Answer 11

using a compass

Question 12

what is the earth’s magnetic field due to?

Answer 12

due to the earth’s core

Question 13

what happens when a current flows through a conducting wire?

Answer 13

a magnetic field is produced around the wire

Question 14

what does the strength of the magnetic field depend on? (2)

Answer 14

• the size of the current,

larger current = stronger magnetic field
- distance ,
closer = stronger

Question 15

what happens when you change the direction of the current?

Answer 15

you also change the direction of the magnetic field

Question 16

how can you prove a magnetic field around the wire using a compass?

Answer 16

when the current is turned off –> compass needle lines up with earth’s magnetic field

when current is turned on —> compass needle deflects

Question 17

what rule is used to work out the direction of the magnetic field produced by a wire?

Answer 17

Right hand grip rule

Question 18

what does the right hand grip rule show?

Answer 18

the direction of the magnetic field produced by a wire

Question 19

how do you increase the strength of the magnetic field (in an electromagnet)

Answer 19

coil the wire

Question 20

3 ways to increase the strength of the magnetic field produced by a solenoid

Answer 20

1. increase the size of the current
2. increase the number of turns of the coil
3. place piece of iron inside solenoid –> iron core

Question 21

what are electromagnets?

Answer 21

solenoid containing iron core

Question 22

what is the motor effect?

Answer 22

when a conductor e.g a wire is carrying a current, it experiences a force in a magnetic field

Question 23

when is a magnetic field produced

Answer 23

when a current moves through a wire

Question 24

what is magnetic flux density a measure of?

Answer 24

the strength of the magnetic field

Question 25

what is the equation for force?

Answer 25

force = magnetic flux density x current x length

Question 26

what are 3 factors affecting the size of the force?

Answer 26

1. magnetic flux density
2. current
3. length of conductor

Question 27

what information can scientist find out about a galaxy when they measure the size of the red- shift the galaxy produces?

Answer 27

its distance from the earth

Question 28

what does the observation of red shift suggest is happening to the universe?

Answer 28

the universe is expanding

Question 29

what is the interface?

Answer 29

the boundary between one medium and another

Question 30

when are waves NOT refracted?

Answer 30

if they are travelling along the normal