Magnetism, Electrodynamics Flashcards by Casey Carden

where are some magnets located in the x-ray room?

detents and stators for the induction moter

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what is the polarity of magnetic material

the direction of the spin south to north

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what does MRI measure against?

the hydrogen spin state

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inside a magnet exists

magnetic force

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outside of a magnet exists

a magnetic field

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magnetism is the ability of a material to attract:

iron, cobalt, nickel

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name some natural magnets

Earth, lode stone

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name some artificial magnets and materials

hard steel, alnico. bar magnet, horseshoe magnet

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temporary magnets produced by the means of electrical current

electromagnets

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how can materials be magnetized?

heating and striking steel near magnet, hitting iron with a magnet

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how can magnets be demagnetized?

hitting it, heating it, alternating current

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magnetic moment

magnetic material has 2 or more electrons spinning in one direction, causing charges to line up

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domain

polarity within a magnet or the direction of the spin

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when magnetic materials are magnetized, how do poles line up?

dipoles (south and north) line up in one direction

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when magnetic materials are non-magnetized, charges do what

charges spin randomly, cannot attract cobalt and nickel

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the alignment of magnetic force within and around a magnet

lines of force

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internal lines of force

magnetic force (south to north)

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external lines of force

magnetic field (leaves north end of internal magnet, loops around to south end and back in)

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transferring magnetism to a non magnetized object

magnetic induction

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when a non-magnetized object is introduced to a magnet, what is its polarity?

non-magnetized object assumes the opposite polarity of the magnet introduced

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the ability of a material to become magnetized

permeability

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materials with high permeability

iron fillings

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material with low permeability

steel

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ability of a material to retain its magnetism

retentivity

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what material has high retentivity

steel

what material has low retentivity

soft iron

magnetic saturation

a point in which a material cannot become any more magnetized

ferromagnetic classification of matter

strongly attracted by a magnet (iron, cobalt, nickel)

paramagnetic classification of matter

weakly attracted by a magnet, low permeability (platinum)

non-magnetic classification of matter

not attracted to a magnet (wood, paper, plastics)

diamagnetic classifications of matter

repelled by a magnet (beryllium and bismuth)

magnetic field surrounding the earth

6 x 10^-6 Tesla

magnetic field of MRI in Tesla

2-4 Tesla used in MRI

Resistance is measured in

Ohms

Current is measured in

Amps

Power is measured in

Watts

Potential difference is measured in

Volts

meaning of V = I x R

Ohm's Law, 1 volt is equal to 1 amp of current flowing with 1 ohm of resistance

where can current flow?

in a vacuum, gas, ionic solution, and metallic conductor

what does current measure

the amount of electrons passing by 1 point

difference between electric charges

potential difference (volt)

electrical charge flowing per second

current (amp)

hinders or opposes the flow of current

resistance (ohm)

EMF stands for

electromotive force

what is the maximum difference in potential between electrodes

EMF or electromotive force

measure of how freely electrons can move through material

conductance

conductance is the opposite of

resistance

conductance is measured in

siemens

EMF is measured in

volts

what is the only direction current flows?

from excess to deficiency

formula for Power

P = V x I

formula for Power Loss

PL = I^2 x R

potential difference which will maintain a current of one ampere in a circuit of one ohm of resistance

volt

amount of electrical charge flowing per second unit

ampere

measurement of an ampere in coulomb

6.25 x 10^18 free electrons per second

resistance of a standard volume of mercury under standards conditions unit

ohm

reciprocal of resistance measured in siemens

conductance

what does resistance depend on?

material coefficient, length, cross-sectional area, temperature

if material coefficient increases, what happens to resistance?

increases

if the length of a conductor increases, what happens to resistance

it increases

if the temperature of a conductor increases, what happens to resistance

friction increases, so resistance increases

if the cross sectional area increases, what happens to resistance

resistance decreases (think bigger cable, less resistance)

what meter measures potential difference?

voltmeter

what meter measures current?

ammeter

what does a galvanometer measure?

either measures voltage or amperage depending on how it is placed in a circuit