magnetism + electromagnetism

Question 1

what is the region around a magnet called?

Answer 1

magnetic field

Question 2

what are permanent magnets?

Answer 2

they produce their own magnetic field

Question 3

what are induced magnets?

Answer 3

they become a magnet when placed in a magnetic field

Question 4

what way do the arrows on field lines run?

Answer 4

north to south

Question 5

what is flux density?

Answer 5

density of the field lines - indicates the strength of the field at that point

Question 6

what does the compass needle align with?

Answer 6

earths magnetic field

Question 7

what direction does the compass needle point?

Answer 7

magnetic north

Question 8

what happens when a current flows in a conducting wire?

Answer 8

a magnetic field is produced around the wire

Question 9

what does the direction of the field lines depend on?

Answer 9

the direction of the current

Question 10

what does the strength of the magnetic field depend on?

Answer 10

the size of the current and the distance from the wire

Question 11

how is a solenoid formed?

Answer 11

when a wire is looped into a cylindrical coil

Question 12

how can you increase the strength of the magnetic field?

Answer 12

shape wire into a solenoid, add an iron core

Question 13

what is the motor effect?

Answer 13

when a current carrying conductor is placed in a magnetic field it experiences a force

Question 14

what is the motor effect caused by?

Answer 14

the field created by the current interacting with the magnetic field

Question 15

how can the force be increased?

Answer 15

increase size of current, length of conductor or flux density

Question 16

what is the equation for force?

Answer 16

force = magnetic flux density x current x length of wire within field

Question 17

what happens if the current or magnetic field is reversed?

Answer 17

direction of force is reversed

Question 18

a current carrying coil in a magnetic field will…

Answer 18

rotate

Question 19

how do loudspeakers and headphones produce sound waves?

Answer 19

they use variations in an alternating current to produce sound waves

Question 20

what is the generator effect?

Answer 20

when conductors and magnetic fields interact, a potential difference is induced

Question 21

how can potential difference be induced (generator effect)?

Answer 21

an electrical conductor moving relative to a magnetic field
c change in magnetic field around a conductor

Question 22

what will reversing the direction of the movement or magnetic field do?

Answer 22

reverse direction of any induced current

Question 23

what does an induced current produce?

Answer 23

a magnetic field that opposes the original change or change in magnetic field

Question 24

what is the generator effect used in?

Answer 24

alternators generate an alternating current

Question 25

what does the use of the split-ring commutator mean?

Answer 25

once the coil has passed the upright position, the connections are reversed. as a result the direction of the current output is always in the same direction

Question 26

for alternators, what is the frequency of the alternating current?

Answer 26

the speed of rotation

Question 27

what does a basic transformer consist of?

Answer 27

a primary and secondary coil wrapped around a soft iron core

Question 28

what would happen if transformers were 100% efficient?

Answer 28

power output would be the same as power input