Magnetism Flashcards
Define Flux density
A concentration of magnetic lines of force ( flux )
Define reluctance
The opposition to magnetic flux
Define residual magnetism
The amount of magnetism that remains after magnetic force is removed
Define retentivity
The ability to retain magnetism
Define permeability
The ability to concentrate magnetic flux ( allowing flux to pass through )
Define saturation
When all domains are aligned and magnet can no longer retain magnetism
What are the three classifications for magnetic materials
Ferromagnetic (easily magnetized)
Paramagnetic ( can be magnetized )
Diamagnetic (cannot be magnetized)
How are hysteresis losses minimized
By adding silicon to the core
How are eddy currents minimized?
Laminations
State faradays law.
Relative motion between a conductor and a magnetic field will induce a voltage into the conductor.
State Lenz’s law.
Induce voltage will cause a current to flow in such a direction that it’s magnetic effect will oppose the change that produced it.
Define inductance.
The opposition to a change in flow of current ( symbol is L )
List three factors affecting the magnetic strength of an electromagnet
Core material
Number of turns in the length of conductor
Current
When flux lines of a moving magnet cut across a stationary conductor by
Relative motion
The strength of a magnetic field is affected by what three things
Core
Current
Number of turns
In order to produce a voltage in a conductor, the motion that must exist between the conductor and magnetic field is known as
Relative motion
Define flux
Magnetic lines of force
Describe hysteresis loss
Flip. Flopping of magnetic domains causing friction, which produces heat, this heat is known as hysteresis loss.
Using the left hand rule what does the thumb indicate
The thumb indicates the direction of current flow
Name two types of iron losses
Hysteresis and eddy currents
Why are iron cores laminated
To minimize eddy current loss
