PHEP 15 Flashcards
Describe flux density? (think measurement)
Its the amount of flux per unit area
The strength of the magnetic field depends largely on?
The material involved and the extent to which the material has been magnetized.
What produces the strongest artificial magnets?
Induced Magnetism (Electromagnets)
Magnetism is a ______.
Force
What are the three important facts about force lines?
no lines cross
all lines are complete
all lines leave the magnet at right angles to the magnet.
What can be done to build a stronger magnetic field?
Add one or more turns of wire.
What happens when a conductor is moved through a magnetic field?
A voltage is induced in the conductor.
The direction of current flow depends on?
The direction of flux cutting and the direction of the magnetic field.
State Lenz’s Law
In all cases of Electromagnetic induction, all induced EMF’s counter the motion producing the EMF.
Or more simply, for every force there is a counter force set up which tends to oppose the first force.
Reluctance in a _____ circuit corresponds to ______ in an electric circuit.
magnetic
resistance
Total flux divided by cross-sectional area gives you?
The flux density.
The amount of flux is measured by the number of lines, called ________.
Maxwells
How many magnetic fields are involved when discussing induced magnetism?
Two
magnetic field
conductor field
What direction are the fields traveling in when discussing induced magnetism?
The magnetic field travels in a straight line form the North to South poles.
The conductor field is a circular field surrounding the conductor.
Permeability corresponds to _______ in an electric circuit.
Conductivity
Permeability is a measurement of?
The relative ability of a material to carry flux.
Permeability is inversely proportional to?
Flux density.
Describe why Iron flux density can no longer increase after as the amp turns are continually increased?
Because the permeability of the Iron as decreased due to saturation.
What can be done to increase the flux density of a material after it’s become saturated?
Nothing.
When turns of a conductor are wound about an Iron core, an ___________ results.
Electro-magnet.
Induction is the process of generating an?
Electrical voltage in a conductor.
Mutual Induction is the transfer of electrical energy from one ______ to ______.
coil or circuit
to
another coil or circuit
What is inductance?
The ability of a coil or circuit to produce a counter-voltage within itself by self-induction.
What determines a coil’s inductance?
The length
The number of turns
The diameter, and
The permeability of the core.
Inductance is measured in ________.
Henries.
Induction is a _________, inductance is an _______, and inductive reactance is a ________.
Process
Ability
Quantity
The driving force causing a magnetic filed is known as?
Magneto-motive force
