Magnetic Fields Flashcards
What is a magnetic field?
À région where magnetic materials (e.g. Iron) and also where wires carrying currents experience a force acting on them
How can magnetic fields be represented?
By field diagrams
What is the rule for field diagrams?
Thé arrows on the field lines always point from the North Pole of the magnet to the South Pole
What happens when a current flows through a wire?
A magnetic field is created around the wire
The field is made up of concentric circles with the wire in the centre
What is the magnetic field inside a coil of wire (a solenoid) Like?
Strong and uniform
What is the current outside the coil like?
Just like the one around the bar magnet
What happens if you stop the current?
Thé magnetic field disappears
What is an electromagnet?
À magnet who’s field can be turned on and off with an electric current
How can you increase the strength of the magnetic field around a solenoid?
By adding a magnetically ‘soft’ iron core through the middle of the coil
What is a magnetically soft material?
A material that magnetises and demagnetises very easily
What happens as soon as you turn off the current?
Thé magnetic field disappears, the iron doesn’t stay magnetised
This is what makes it useful for something that needs to be able to switch its magnetism on and off
Why must an electromagnet be constantly supplied with current?
That’s what produces the magnetic field
If current stops it bring magnetic
What are examples of magnetic fields being used?
Electromagnets are used in some cranes e.g in scrap yard and steel works
Used to attract and pick things up made from magnetic materials like iron and steel
What would happen if an ordinary magnet was used ?
the crane would be able to pick up the metal but then wouldn’t let go
Using electromagnet means it can be switched on when you want to pickattraxt and stuff up and off when you want to drop it
