Electromagnetism Flashcards
(13 cards)
Why does the compass needle turn when placed near the bar magnet
Forces between the compasses poles and the magnets poles turns the needle
What happened in 1880
Hans oersted a Dutch scientist discovered an electric current produces a magnetic field
Why are feild lines parallel in a solenoid
Shows strength of magnetic field as uniformed
How to measure strength of an electromagnet
Mass of iron it attracts can be measured the more iron it attracts the stronger it is
Four uses of electromagnets
Extract small pieces of iron from eyes in hospitals
Lifting or moving cars and scrap yards
Electronic magnet relays or conveyor belts
MRIs
How can current flow be increased when moving a conductor through a magnetic field
Move wire faster
Increase strength of magnet
How can alternating current be generated
By electromagnetic induction
How can increased current be induced in the coil when moving conductor in a wire
Increase the number of turns of the solenoid
increased strength of magnet
move magnet faster
increase area of coil
What principle is used in transformers
When the switch is closed there is an increase in current in the primary coil which induces a momentary current in the secondary coil
When study current flows in the primary cause there is no current in the second record
As the switches open there’s a momentary current in the primary cause but this time in the opposite direction
Alternating current generators
As coil rotates one side moves upwards through the magnetic field and the other side moves downwards using the Fleming’s left hand rule a current is induced in one direction
After rotating 180 degrees the side moving upwards through the magnetic field no moves downloads and the same moving downwards through the magnetic field no moves upwards due to the wires no moving an opposite direction the current also flows in opposite direction
As current repeatedly changes every 180 degrees due to coil rotating, generating an AC current
What do transformers do
Changes and alternating current from one value to another using two coils of insulated wire wrapped around an iron core
What happens within a transformer
Alternating current passes through the primary coil wrapped around a soft iron core that changes the current producing a magnetic field change that induces an AC current in the secondary coul
What is home voltage
230 volts
