Magnetics

Question 1

what are the 2 types of magnets

Answer 1

permanent and temporary

Question 2

where is the magnetic field of a magnet’s strongest

Answer 2

at the poles

Question 3

what are the 4 magnetic materials

Answer 3

iron
nickel
cobalt
steel

Question 4

what is a permanent magnet

Answer 4

a magnet that has North and south poles all the time

Question 5

what is a temporary magnet

Answer 5

a magnet that is made by bringing a permanent magnet near it. and it will lose its magnetic field when the permanent magnet is removed. it does not have poles

Question 6

what is an example of a temporary magnet

Answer 6

electromagnets

Question 7

what is a plotting compass used for

Answer 7

to plot the shape and direction of the magnetic field lines

Question 8

an electric current will create a…

Answer 8

magnetic field

Question 9

describe the shape of a magnetic field made by current flowing through a wire

Answer 9

a series of concentric circles

Question 10

what method can be used to find the direction of the magnetic field created by a current-carrying wire

Answer 10

right-hand method

Question 11

what 2 factors affect the strength of a magnetic field created by a current-carrying wire

Answer 11

size of current
distance from wire

Question 12

what is a solenoid

Answer 12

a coil of wire that carries a current

Question 13

describe the magnetic field of a solenoid

Answer 13

• strong uniform magnetic field along the centre of the solenoid
• weak field outside solenoid as opposing field lines cancel it out

Question 14

what is the motor effect

Answer 14

when a current-carrying wire is placed near a magnet the 2 interacting magnetic fields cause the wire to experience a force

Question 15

what rule can be used for motor effect

Answer 15

flemings left-hand rule

Question 16

what does each finger symbolize in the left-hand rule

Answer 16

Thumb - the movement of the wire
first finger - magnetic field direction
second finger-wire current direction

Question 17

in the motor effect, if the current is parallel to the field lines there is…

Answer 17

no force

Question 18

what 2 factors can be changed to increase the size of the force in the motor effect

Answer 18

current size
magnetic field strength

Question 19

what does a split ring do

Answer 19

swaps the connection to the battery over every half-turn so the coil continues to spin in the same direction

Question 20

what is the formula for the force experienced by the wire (in motor effect)

Answer 20

force = magnetic flux density * current * length of wire

Question 21

what is electromagnetic induction

Answer 21

when a coil of wire is moved in a magnetic field to induce a current in the wire due to the interacting magnetic fields of the coil and wire

Question 22

what 2 factors can be changed to change the direction of the current induced in electromagnetic induction

Answer 22

changing the direction the wire is moving
changing the direction of the magnetic field

Question 23

what 3 factors can be changed to change the size of the current induced in electromagnetic induction

Answer 23

move wire faster
use stronger magnets
use more loops of wire

Question 24

what is a generator

Answer 24

a machine that uses electromagnetic induction to generate electricity

Question 25

what is the difference between dynamos and alternators

Answer 25

alternators create AC
dynamos create DC current

Question 26

how does a dynamo create a DC

Answer 26

every half turn the contact with carbon brushed is broken by a gap in the slip rings so that a current in the opposite direction is not induced

Question 27

what piece is used by the dynamo to create DC

Answer 27

split rings

Question 28

what idea does a microphone use to work

Answer 28

electromagnetic induction

Question 29

what idea does a loudspeaker use to work

Answer 29

motor effect

Question 30

what does a microphone do (energy)

Answer 30

converts kinetic energy into electrical energy

Question 31

what does a loudspeaker do (energy)

Answer 31

converts electrical energy into kinetic energy