magnetism and electromagnetism Flashcards
induced vs permanent magnet
- permanent- produces own magenti field
- induced- becomes magent inmagnetic filed- always attracted to permanet magent
magnetic materials
- iron
- cobalt
- steel
- nickle
define magentic field
- region around a magnet where a force acts on another magnet or magnetic material
current flowing through wireq
produces magnetic field
use right hand rul
q
what does the stength of the magnetic field from a current depend on
- size f current
- distance from the wire
solenoid
coiled wire, increases stength of magnetic field
how to increase strength of manetic filed around solenoid
- increase size of currrent
- increases turns on coil
- add iron core
electromagnet
and 2 uses
- solenoid with iron core
- doorbell
- relay
how does a relay work
- 2 seperate circuits
- one with an electromagnet- low voltage
- one iwth high volatge and contacts as swithc- controlled by a spring with an iron block inbetween
- when switch of 1st circuit is on- manetic field pulls contacts together
how does a doorbell work
- buzzer turns switch on
- that creates magnetic filed around electomagent
- that pulls iron block to field
- taps the bell
- resets circut
The motor effect
occurs when a wire with current flowing through is placed in a magnetic fied and exerts a force
(2 interacting magentic fields)
how to increase force in motot effect
- ^ size of current
- stronger magnets
- wire perpendicular to magnetic field
Flemmings left hand rul
- thumb- thrust/force
- first finger- magnetic field
- second finger- current
electric motor
- motor effect but with loop of wire
- opposite directions on each side- different directioned forces
- however will stop at 90^
- split ring commutator- each split part connected to loop and then to ciruit wth conductor brushes
- at 90^ rings break circuit- not connnected- no current- no force- momentum continues
how do loudspeaker/ headphones work
- coil on a perment magnet- E SNS- with cone
- coil- AC- changing current- chagimg magnetic force- intereaction wth permemt magent’s magnetic force- changing diretion foce
- coil oscillates- cone oscillates- air oscillates- sound waves
generator effect
- when wire moved up and down through mgetic field- potebtial difference is induyced (force on electron- move- pd)
- pd keeps swapping direction up and down (one direction- one movement of leectrons)
- in complete circuit- induced current- ac
- alsoooo moving mane through a coil of wire
how to increase sixe of pd in generator effect
- stronger magneticfield
- coil- more turns
- move more rapdly- wire
altenator
AC
- coil of wire roatating in mf connected to 2 metal rings- communators which allwos current to pass out of coil
- coil moving- induces pd- constantly changing- acb & pd
dynamo
DC
- coil of wire rotating trhoufgh mf with split ring communator
- basically opposite of motor- purposfuly moving coil
microphone
- sound waves hit diaphragm which vibrates
- attached to coil of wire that oscillates in and out of magnetic field from E magnet
- creates pd which can be amplified etc
transformers
- AC through primary coil around iron cOre
- ^ curent creates CHANGING magnetic field
- iron core transmits ^ to secodary coil
- chaning mf- induces potential difference in coi
- current flows
why transformers AC & iron core & eqaual turns (non- step)
- AC- changing magnetic field
- iron core- easily magnified
- same pd- IF 100% effeicient
ste up transformer- turns in coils
SECONDARY> primary
step down transformer- turns in coils
PRIMARY> secodary
