Ch.4 XRay Circuit Basic Terminology

electrons and protons

smallest UNIT of charge

electrodynamics

study of electric charges in motion and ehat we often consider as “electricity”

coulomb

The SI unit of electric charge

T

electrical charges reside only on the external surface of conductors.

T/F

electrostatic force

how much attraction or repulsion are between 2 charges

directly

electrostatic force is _____ proportional to the product of their quantities ; MORE charge, MORE attraction/repulsion

ex: if you DOUBLE the number of electrons then you DOUBLE repulsion

inversely

electrostatic force is ____ proportional to square of the distance between them

-if charges get further away from each other, then they are going to have lesser repulsion/attraction

-increase distance, decrease electrostatic force (1/4)

-decrease distance, increase electrostatic force (x4)

F

concentration of charges on a curved surface of a conductor is greatest where the curvature is least

T/F

negative charges (electrons)

what kind of charges are free to move in solid conductors?

electric potential

the ability to work because of a separation of charges or potential difference between two points in an electric field.

volts

what is electric potential measured in?

electric potential

having more electrons at one end of a wire and less electrons (positive charge) at the other end of the conductor

-electrons flow from high to low

conductors

materials with a large number of electrons free to move about that allow electric current to flow easily.

insulators

materials inhibiting flow of electrons and do not conduct electricity well. They have few free electrons.

conductors

copper, gold, nickel

insulators

glass, plastic, wood

electric potential

the more separated electrons are from positive charges, the higher the ______ differences

electric current

flow of electrons in conductor; how many electrons flowing

ampere

unit measurement for electrical current

ohm

unit measurement for electrical resistance

electrical resistance

property of an element circuit that resists or impedes the flow of electricity

volts

potential difference that will maintain a current of 1 ampere a circuit with a resistance of 1 ohm.

-difference in electrons and protons positive and negative charges that has to happen to move 1 amp of circuit with resistance of 1 ohm

volts

___is also an equal to amount of work (in joules) that can be done per unit of charge

amperage; ampere

defined as the amount of current flowing with electric potential of 1 volt in a circuit with a resistance of 1 ohm

(for this to exist, there has to be electric current to flow)

amperage; ampere

also known as measuring intensity of electrical current

ohm’s law

shows relationship between voltage, amperes, and resistance

(potential difference) voltage = (current) amperes x resistance

V=IR

ohm

defined as electrical resistance = to the resistance between 2 points along a conductor that, when a potential difference of 1 volt is applied, produces a current of 1 ampere

resistance length

longer conductor, more resistance than shorter conductor

cross-sectional

a conductor with a large _____ area has LOWER resistance than one with small b/c there is a greater external surface area which electrons can travel

bigger = less resistance

T

with metallic conductors, the resistance becomes GREATER as the temperature of the conductor rises

T

material, length, cross sectional area, temperature

4 things the amount of resistance depends on

closed

what kind of pathway allows electricity to flow, creating an electrical circuit?

x-ray circuit

complex circuit that has different voltages and current flowing through different sections ( 3 areas w/ 3 diff types of circuits)

open

what kind of circuit is broken, stopping electricity to flow?

direct current (DC)

current travels only one direction through time with constant voltage

eg. flashlight turned on

alternating current (AC)

current that travels one direction, stops, then travels the opposite direction creating pulsating voltage

battery

device that produces electrons through chemical reaction. stores electric charge for long term and provides an electric potential

battery

capacitor

device that is like a battery (stores electrical charge) but works very differently in that it cannot produce new electrons and stores the charge only temporarily

-has to be recharged

capacitor

diode

a one-way valve device that allows electrons to flow in only one direction

eg. solid state rectifier

diode

fuse

section of special wire, usually encased in glass, that quickly melts if the current flow rises excessively, thus opening the circuit (stops flow of electricity)

circuit breaker

if current flow rises excesively, this internal switch is tripped (opened), stopping the flow of electricity

rheostat

an adjustable or variable form of resistor

ex. dimmer

fuse

circuit breaker

resistor

rheostat

switch

device that opens a circuit (breaks the pathway)

transformer

device that can increase/decrease voltage by as predetermined amount

switch

transformer

magnetism

ability of material to attract iron, cobalt, or nickel

magnetic domains

when dipoles/”magnetic magnets” form groups of similarly aligned atoms

flux

magnetic field consists of lines of force in space

south to north

which poles do lines of flux travel INSIDE of a magnet?

north to south

which poles do lines of flux travel OUTSIDE of a magnet? (creating elliptical loops)

repel, attract

like poles ____, opposite poles ____.

directly

force of attraction or repulsion varies ___ withj the STRENGTH of the poles

inversely

force of attraction or repulsion varies ____ with the square DISTANCE between them

tesla

magnetic force SI unit

nonmagnetic, diamagnetic, paramagnetic, ferromagnetic

4 categories that materials can be classified by their magnetic properties

nonmagnetic

not attracted to magnetic fields at all

eg. glass, wood, plastic

diamagnetic

weakly repelled by magnetic fields

eg. water, mercury, gold

paramagnetic

weakly attracted to magnetic fields

eg. aluminum, platinum, gadolinium

ferromagnetic

strongly attracted to magnetic fields and can become permanently magnetized.

eg. iron, nickel, cobalt

electromagnetism

any flow of electrons, whether in a space or in a conductor, will be surrounded by a magnetic field

-a MOVING magnetic field can create an electric current

electromagnetic induction

moving a conductor (such as copper wire) through a magnetic field, induces an electric current in that conductor

-when you make electrons move, you create electrical current

mutual induction

the induction of electricity in a second coil by a moving magnetic field

-when moving magnetic field is placed NEAR a secondary coil, electricity is induced to flow in that coil

self induction

because we have an expansion and contraction of magnetic flux around the wire, it is going to “cut” the coils of the wire as it’s coiled

-cutting creates a current within the same conductor that opposes the original

-occurs with one coil of wire; when the current in a coil changes, it induces a voltage in the same coil that opposes the change.

electric generators

devices that convert some form of mechanical energy into electrical energy using electromagnetic induction to produce electricity.

electric motors

devices that convert electrical energy to mechanical energy using electromagnetic induction

-taking electric current and causing motion

transformers

devices used to increase or decrease voltage (or current) through electromagnetic induction

step-up transformer

increases voltage, increase amp, decrease current

step-down transformer

decreases voltage, decreases amp, increases current

current

as we increase voltage with a step-up trransformer, what decreas

amp

as we increase voltage with a step-up transformer, what also increases?

autotransformer

A type of transformer that allows for voltage adjustments by tapping into different points of the winding, typically used in X-ray circuits to control incoming voltage.

-operates with self-induction

-it has only one coil of wire around a central magnetic core serving as both the primary and secondary coil