3.10 Magnetism Flashcards
What are the 2 theories of magnetism called?
Webers theory and Domain Theory
Define magnetic flux
The measurment of a total magnetic field (number of field lines) which passed through a given area
What is the SI unit of magnetic flux?
Weber
What are the 3 types of magnetic material called?
Ferromagnetic, Diamagnetic, Paramagnetic.
What is ferromagnetic material
Strongly attracted by a magnetic field eg: iron, steel, nickel, cobalt
What is a Diamagnetic material?
Materials which are repelled by magnets such as zinc, mercury, lead, sulfar, copper, silver
What is a paramagnetic material?
Materials that are not strongly attracted to a magnet, aluminum, tin, magnesium
If a ferromagnetic material is not already a magnet what happens when its placed near a magnet?
It automatically turns into one.
How is a magnetically shielded area created?
Flux lines will deviate from an air path to pass more readily through a ferromagnetic path, an easy way to magnetically shield a component is to use a soft iron around the case or instrument.
If an electric current is flowing in a conductor towards the page, which way is the mag flux rotating?
Anti Clockwise.
If electric current is flowing in a conductor out of the page, which way is the mag flux rotating?
Clockwise.
If current is flowing in the same direction through 2 parallel conductors which way are the conductors getting pushed by the magnetic fields?
Towards each other.
If current is flowing in opposite directions of 2 parallel conductors which way is the magnetic field acting on the conductors?
Pushing them away from one another.
Which rule shows the direction of flux flowing around a conductor?
Left hand grasp rule.
Which rule shows the direction of the magnetic field (N and S Poles) of a coil.
Left hand grasp rule for polarity, fingers are wrapped around coil in direction of current flow, thumb is pointing to north pole.
Define coercive force.
The amount of reverse magnetic field that is required to bring the magnetic flux down to zero.
Define retentivity
The left over magnetic flux in a material when the magnetising force is returned to zero.
What materials will create a LArge hysteresis loop?
Hard magnetic materials
What materials will create a thin hysterisis loop?
Soft magnetic materials
