MRI P2

Electrodynamics

The science of electricity charge in motion

Electric current

A flow of electric charge

Direct current

If the energy source propels electrons in only one direction

Phase

All electrons are moving in the same direction with the same velocity -they are said to be in ______

Ohm’s law

The voltage across the total circuit or any portion of the circuit is equal to the current times the resistance

Capacitive, inductive, resistive

3 types of impedances

Resistive

The work done on the device changes the electric energy into heat

Conductors

Any substance through which electrons flow easily

Insulator

Any material that does not allow electrons to flow

Semiconductors

Materials lie between conductor and insulator

Superconductors

The electric resistance of a material is zero

Power

The rate at which energy is used or work is produce

electric potential

Electric current flows because of _______

Energy

_____ is required to move a charge through an electric potential

Magnetism

A field effect associated with certain types of material said to be magnetic

Magnetic domains

Smallest region of magnetism

Electron configuration

Describe where electrons are located around the nucleus of an atom

Ferromagnetic magnets

These materials make the strongest magnets and are used singly and in combination with MRI permanent magnets

Ferromagnetic magnets

Easily magnetized and have a magnetic susceptibility greater than 1

Magnetic susceptibility

The degree to which a material becomes magnetized in response to an applied magnetic field

Paramagnetic

These materials have a magnetic susceptibility less than 1

Paramagnetic

They are weakly influenced by an external magnetic field but do not exhibit measurable magnetic properties of their own

Diamagnetic

Have negative magnetic susceptibility and in fact are slightly repelled by magnets

Attraction/repulsion

Like magnetic poles repel and unlike magnetic poles attract

Magnetic permeability

Property that basically allows magnetic lines of force to pass through a material

Electromagnet

It owes its magnetism to an electriccurrent, which induces magnetism but only while the electric current is flowing

Gauss’s law

Magnitude is proportional to the product of the two interacting magnetic pole