P4.1 Flashcards
What do field lines represent?
They represent the the magnetic flux
What is the number of field lines passing a particular area called
It’s the magnetic flux density
What way to the magnetic field lines move in and what does the density show
They move in the way that makes the field lines shorten
It shows the strength of the magnetic field
What is a permanent magnet
It’s a magnet that retains its magnetic properties even in the absence of an inducing field or current
What happens in the domain model of a permanent magnet
It’s made up of small magnetic regions called domains that line up
What is an induced magnet
The substance like iron or steel becomes magnetised by a magnetic field. It’s produced from the force of the field radiating from the poles of a magnet
What happens on the domain model of an induced magnet
When in a magnetic field, all the domains like up
What happens to the domains in hard and soft materials
In hard materials it continues to be lines up after the magnetic field is removed but in soft the domains return to their original position
Why do compasses point north
Earth behaves like a large bar magnet and scientists are not sure why but think it may be due to the convection currents in the molten iron core of the earth .
Compasses are weighted due to the Earth’s magnetic field being like a bar magnet, so they lie horizontally. The angle between the field lines and the Earths surface is the dip. It’s 90 degrees at the north and south magnetic poles and 0 at the magnetic equator.
How can you show that current creates a magnetic field
Use compasses around a current carrying wire
What did Oersted find out
If the current was coming towards you then the field lines were anti-clockwise
1ST RIGHT HAND RULE
Thumb is current and curling of fingers in magnetic field lines
What does the strength the field around of a wire depend on
Magnitude of current (bigger current = stronger field)
Distance from the wire (nearer to the wire = stronger field)
What is the strength of Magnetic fields measured in
Teslas
What’s the earths magnetic field
0.1mT which is 0.0001T
How does the solenoid enhance the magnetic effect
It has many parallel loops to make a coil and each wire has its own magnetic field and adding more increases the strength of the field. Increasing current in the wire also increases the field. Putting a magnetic material (soft iron core) inside the core makes it even stronger as it produces an induced magnet.
