ELECTRICITY, ELECTROMAGNETISM, MOTORS, GENERATORS, TRANSFORMERS, RECTIFICATION RAD 1130

1. move conductor through a stationary unchanging strength magnetic filed 2. move the magnetic lines of force through a stationary conductor with an unchanging strength magnetic field. 3. vary the magnetic flux strength from a stationary magnet through a stationary conductor

3 ways to create motion between lines of force and conductor

direct current

an electric current that flows in one direction steadily

nonconductor (insulator)

an object that doesn't conduct electricity; electrons can't flow through

ionic solutions

can cause electrons to migrate to positive or negative poles during electrolysis

simply pop open and can be reset once the problem is located and removed from the circuit

circuit breakers

single ring that is divided in half, with each half connected to one end of the armature wire

commutator ring

any material through which electrons may freely pass

conductor

armature, set between opposing magnetic poles

conductor of generator

unit of electric charge

coulomb

earth

defined as zero or ground potential

Number of loops of the wire, Current strength, Permeability of the core

determines strength of solenoids & electromagnets

beryllium, bismuth, lead. weakly repelled by magnetic fields

diamagnetic

inversely proportional relationship to resistance

diameter of conductor

A _________ ___________ generator is made by exchanging the slips rings for a commutator ring

direct current

the addition of resistances, the increasing amperage can short circuit the entire system

disadvantage to parallel circuits

path along which electrons flow; may be wired as series circuits or parallel circuits

electrical circuits

wrap a coil of wire around a ferromagnetic core

electromagnet

protect radiographer from electrical shock by isolating control buttons on the x-ray console from the actual circuit in which high voltage is flowing

electromagnetic relays

any moving charge produces a magnetic field

electromagnetism

temporary, produced by moving electric current. Any flow of current produces a magnetic field, flow stops, magnetic field collapses

electromagnets

other termed used for potential difference

electromotive force (emf)

electric current

electrons moving in the same direction

diameter of coil, its length, current passing along the coil

factors that govern effectiveness of solenoids and electromagnets

iron cobalt, nickel, highly permeable and susceptible to induction, majority of dipoles are in same direction

ferromagnetic

three methods of electrification

friction, contact, induction

metal tab that melts when dangerously heated, need to be replaced, and cannot be reset

fuses

converts mechanical energy into electrical energy

generator

left hand motor rule

index finger- points in the direction of the magnetic lines of force middle finger- points in direction of the conventional current thumb- indicates direction the conductor will move

when current reverses, previously established N and S pole induce an opposing potential difference. going against incoming supply of electrons

inductive reactance

1. Repulsion-Attraction 2. Inverse Square Law 3. Magnetic Poles

laws governing magnetism

as a charged object gets further away, the influencing charge decreases

laws of electrostatics 2. inverse-square law

charges reside on the external surfaces of conductors, and equally throughout nonconductors

laws of electrostatics 3. distribution

greatest concentration of charge will be on the surface where the curvature is the sharpest

laws of electrostatics 4. concentration

electrification occurs because of movement of negative electric charges

laws of electrostatics 5. movement

directly proportional relationship to resistance

length of conductor

Laws of Electrostatics 1. Repulsion-Attraction

like charges repel; unlike charges attract

force fields created when magnetic dipoles orient to create a magnet are called _______

lines of force, lines of flux, or magnetic field

When a nonmagnetized iron bar is brought within the lines of force of a strong magnet, the dipoles will temporarily align themselves with the lines of force passing through the bar

magnetic induction

every magnet has two poles, a north & south

magnetic poles

when a charged particle is in motion a magnetic force field perpendicular to the motion will be created

magnetism

when magnetic dipoles are in a predominant direction

magnetized

the stronger the magnetic field, the ______ lines of flux

more

induction

most important, process of electrical fields acting on one another without contact

device that is supplied with electrical current to produce mechanical motion

motor

result of the interaction of magnetic fields when an electrical current is sent along a conductor that is residing in a magnetic field

motor principle

2 coils close together, primary -supplied with AC current, secondary- induced with AC current

mutual induction

iron oxide remain in earth's field for ages, slowly orienting magnetic dipoles in same direction

natural magnets

3 types of magnets

natural, artificial permanent, electromagnets

wood, glass, rubber, plastic, not affected by magnetic fields and can't be magnetized

nonmagnetic

when magnetic dipoles are randomly arranged, not in a predominant direction they cancel each other out

nonmagnetized

friction

occurs when an object is rubbed against another

unit of measurement for resistance

ohm

several pathways for electrons to flow, each component has an individual branch (homes)

parallel circuit

which circuit operate with greater current through resistances and supply a greater total current from the power supply

parallel circuits

platinum and aluminum, low permeability and weak attraction to magnetic fields

paramagnetic

ease with which a material can be magnetized

permeability

conventional electric current

positive to negative poles for flow, outside

force or strength of electron flow

potential difference

force with which the electrons travel is a function of the difference between the number of electrons in excess at one end of circuit & deficiency at the other. there does not have to be an actual flow of current for the difference to exist.

potential difference

Permits a variable contact to slide along a series circuit of resistant coils

potentiometer or rheostat

P=IV

power

gasses

promote the drift of electron from a negative electrode (cathode) to a positive electrode (anode)

common descriptors of current flow

quantity of electrons, force with which they travel, amount of opposition in current flow

current

quantity, or number of electrons flowing, unit of measurement is amp

the amount of opposition to the current in the circuit is called

resistance

cause significant energy waste in heat

rheostat

coil supplied with AC allows steady flow of electrons, establishes electromagnetic effect for half the cycle.

self induction

A substance that can conduct electricity under some conditions

semiconductor

an electric circuit designed to send electrons through various resistance devices by linking them one after the other (christmas lights)

series circuit

type of curve produced by AC generator is called

sine wave

to convey the electrical current from the armature to the circuit a set of what is used?

slip rings and brushes

conduction wire is looped to form a coil through which current flows

solenoid

detent locks on overhead cranes of x-ray tubes

solenoids

Inside the magnet, the lines of flux travel from:

south pole to north pole

vacuum

space from which air has been removed

conduction coils that turn at the same speed as the generator armature supplying the current

synchronous AC motors

two types of alternating current motors

synchronous AC motors, and AC induction motors

inversely proportional, as temp increases current flow lessens

temperature of conductor

Units for flux density

tesla

laws of electrostatics

1. Repulsion-attraction 2. Inverse square law 3. Distribution 4. Concentration 5. Movement

alternating current

A flow of electric charge that regularly reverses its direction.

the process of electron charges being added to or subtracted from an object

Electrification

electron flow

Electrons move from the highest concentration to the lowest, from negative to positive

The study of electric charges at rest

Electrostatics

1. Strength of magnetic field 2. Speed of motion between lines of force and conductor 3. Angle between lines of flux and conductor 4. Number of turns in conductor

Faraday's Law 4 factors that regulate the strength of induced current

unit of frequency

Hertz (Hz)

induced current flow sets up a magnetic field opposing the action that produced the original current, or simply, induced current opposes any flux change

Lenz's Law

Outside the magnet, the lines of flux travel from:

North Pole and South Pole

V=IR

Ohm's Law

ability of material to stay magnetized

Retentivity

static discharge

The loss of static electricity as electric charges transfer from one object to another

manufactured from a steel alloy (alnico) composed of aluminum, nickel & cobalt. Subjected to strong magnet field and is relatively permanent

artificial permanent

Fleming's right hand rule

thumb- direction of current flow fingers- direction of the magnetic field lines

right hand generator rule

thumb- points in direction the conductor is moving index finger- points in direction of magnetic lines of force middle finger- points in direction of current

what directly relates to ability for a material to conduct

valence energy band (outermost and next-to outermost shell)

potentiometer or rheostat

variable resistor

unit of measurement for potential difference

volt

unit of measurement for power

watt

SI units for flux

weber

contact

when two objects touch, permitting electrons to move from one to another