Electromagnetism/ physics

ELECTROSTATICS

The study of stationary electric charges

ELECTRONS AND PROTONS

Smallest units of electric charge. Equal in magnetude opposite in charge

ELECTRIFICATION

Process of electron charges being added or subtracted from an object

EARTHS PART IN ELECTRIFICATION

Takes in excess electrical charges. Earth is zero or ground potential

COULOMB

The unit used to count electrons in multitudes

1 COULOMB =

1c=6.3 x 10 to the 18th power

ELECTROSTATIC FORCE

Like charges repel and unlike charges attract. These are caused by the electric fields

COULOMBS LAW

The strength of electrostatic force is greater when two objects are closer together and lesser when they are further apart.

COULOMBS LAW PROPORTIONALITY

The electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of distance between them

ELECTRIC CHARGE DISTRIBUTION

Uniform on the surface of a conductor and uniform THROUGHOUT a non- nonconductor

SHARPEST CURVATURE OF CONDUCTOR

Electric charge concentrated along sharpest curvature of the surface and can lead to discharge if nearby object is less negative

ELECTRIC POTENTIAL

Electron charges bunched up on sharp surface have the ability to do work when they discharge. When electrons repel each other and move down a wire they are doing work this is electric current

VOLT (V)

A way to quantify or measure the degree of attraction or repulsion

US ELECTRIC POTENTIAL IS

110 volts

X-RAY ELECTRIC POTENTIAL

220 volts

ELECTRODYNAMICS

The study of electric charges in motion

ELECTRIC CURRENT A.k.A ELECTRICITY

Electrons moving down a wire when an electric potential applied to copper wire

ELECTROCARDIOGRAMS MEASURED IN

Millivolts because electrical towers transmit in thousands of volts

CONDUCTORS

Allow electron flow

NON-CONDUCTORS

DO NOT allow electron flow

EXAMPLES OF CONDUCTORS ARE

Copper, other metals and WATER

EXAMPLES OF NON-CONDUCTORS ARE

Glass, clay, plastics, rubber...

WHAT KEEPS ELECTRONS FLOWING IN PROPER DIRECTION?

The conductor wrapped in an insulator prevents detours that may cause shock

ELECTRON FLOW IS FROM

Negative to positive

CURRENT FLOW IS FROM

Positive to negative

ELECTRIC CURRENT

Is the flow of electrons from a source that generates them

ELECTRIC CIRCUIT

Is that flow of electric current through various components and then back to generating source. (The circuitis a closed path as electrons return to their source.)

RESISTANCE

Is the ease of electron flow through a conductor.

MEASUREMENT OF RESISTANCE IS

Ohm (♎️)

FACTORS AFFECTING RESISTANCE ARE

•conductors conducting ability.

•length of conductor the longer length increases resistance.

•cross sectional diameter, the larger the better.

•temperature, the cooler the better.

IF RESISTANCE INCREASES WHAT HAPPENS TO CURRENT?

Current decreases

HOW IS CURRENT MEASURED?

In Amperes (A)

1 Amp is = to an electric charge of 1C flowing through a conductor EACH SECOND.

NUMBER OF AMPS CAN TELL YOU WHAT?

If there is a large or small quantity of electrons flowing.

OHMS LAW

"THE VOLTAGE ACROSS THE TOTAL CIRCUIT( or any portion of the circuit) IS EQUAL TO THE CURRENT TIMES THE RESISTANCE."

V=IR

YOU CANNOT CHANGE ONE VALUE IN A CIRCUIT WITHOUT CHANGING ANOTHER exaple if you increase resistance but dont change volts then...

If you increase resistance but dont change volts then you must decrease amps.

If you increase volts and dont change resistance then you must increase amps.

SERIES CIRUITS

All circuit elements are connected in a line across the SAME conductor.

(One light bulb goes out the rest of them do as well)

PARALLEL CIRCUIT

Contains elements that Are connected at their ends rather than lying in a line along the conductor.

(One bulb dies the rest are not affected.)

RULES FOR SERIES CIRCUIT

•The total resistance is equal to the sum of individual resistances.

•the current through each circuit element is the same and equal to the total circuit current.

•the sum of the coltages across each circuit element is equal to the total circuit voltage.

PARALLEL CIRCUIT

Contains elements that are connected at their ends rather than lying in a line along the conductor.

RULES FOR PARALLEL CIRCUITS

• the sum of the currents through each circuit element is equal to the total circuit current.

•the voltage across each circuit element is the same and is equal to the total circuit voltage.

• the total resistance is the inverse of the sum of the reciprocals (x vs. 1/x) of each individual resistance.

DIRECT CURRENT

Electrons that flow in one direction. Their wave form is a straight line.

ALTERNATING CURRENT

electrons flow in one direction then reverse and flow in the other direction, a process called oscillation. The waveform for AC is a sine wave.

PARTS ABOVE AND BELOW AC SINE WAVE REPRESENT WHAT?

The part above the straight line represents forward or positive movement of electrons.

The part below the straight line represents reverse or negative movement of electrons.

AC IDENTIFIES AS AS HOW MANY HZ CURRENT?

AC is a 60Hz current and each oscillation requires 1/60 second.

Thats 60 cycles per second.

ELECTRIC POWER

Take the current( number of electrons) times the speed of travel(force of attraction from negative to positive) equals overall quantity of power available.

ELECTRIC POWER MEASURED IN WHAT?

Electric power is measured in Watts (W).

1 Watt equals 1 Ampere of current flowing through an electric potential of 1 volt.

P=IV

MAGNETISM

Polarization of a material.

POLARITY

Existence of opposing negative and positive charges. Versus something having only a negative or positive charge.

WHAT DOES A CHARGED PARTICLE IN MOTION CREATE?

A magnetic field

WHAT TWO WAYS DO ELECTRONS TRAVEL?

1. The electron orbits around the nucleus in its orbital shell.

2. Electrons also rotate on their own axis. (Electron spin.)

ELECTRONS THAT ORBIT AROUND THE NUCLEUS CREATE

They create a magnetic field with this motion that will be Perpendicular to the direction of motion.

CLOSED LOOP MOVEMENT OF AN ELECTRON

The movement of the electron around the nucleus for example, with the magnetic field moving with the charged particle.

ELECTRON SPIN

Electrons that rotate on their own axis create a magnetic field along the axis of the spin.

These magnetic fields are called bipolar or dipolar and have north poles and south poles.

DIPOLES

Normally unaligned but when magnet brought close they align with that magnet creating a magnetic domain.

MAGNETIC DOMAIN

Created when dipoles align making objects behave like magnets.

Naturally occurring ones align with the earth.

NATURALLY OCCURRING MAGNETS

•EARTH is the largest and spins on its axis.

•IRON OXIDE (magnetite) within the earth over time was undisturbed, exposed to the earths influence and remains magnetized

ARTIFICIALLY PRODUCED PERMANENT MAGNETS

•ALLOY CALLED ALNICO is aluminum, nickle and cobalt. It is heated and exposed to an external magnet. As alloy cools it will retain its magnetism

ELECTROMAGNET

Produced via electric current. The electrons create a magnetic field.

STRENGTH OF THE ELECTROMAGNETS FIELD

Depends on the size of the electric current. When the wire is wrapped around an iron core the magnetic field greatly increases

MAGNETIC PERMEABILITY

The ease or ability of becoming magnetized. All matter can be classified by permeability.

NONMAGNETIC

Wood, glass, rubber

DIAMAGNETIC

Weakly repelled by either magnetic pole and cannot be artificially magnetized. Examples are water , plastic and copper

PARAMAGNETIC

Lowish permeability and weakly attracted to magnets. Can be induced to be magnetized but it takes a long time. Loosely influenced by external magnetic field. Examples are platinum and GADOLINIUMWHICH IS CONTRAST OF CHOICE BECAUSE OF ITS WEAK ABILITY TO BE MAGNETIZED

FERROMAGNETIC

Highly permeable and easily induced to become permanently magnetized. Examples are, iron, cobalt and nickle.

MAGNETIC LAWS

1. No smallest unit to magnetism. If you break one magnet it makes two smaller magnets still with north and south poles.

2. Like poles repel and unlike poles attract.

3. Inverse square law; as magnetic fields move far away from each other less influence on each other and if close one is under the influence of the other.

"The magnetic force between teo objects is inversely proportional to the square of the distance between them"

MAGNETIC INDUCTION

Dipoles of ferromagnetic object will align with a magnet thus becoming a magnet only happens with ferromagnetic materials. Technically can happen with paramagnetic materials but it takes forever.

STRENGTH OF A MAGNETIC FIELD

Can be made permanent through heat or long time exposure to a strong magnet removing the influenced magnet will make magetism disappear.

STRENGTH OF MAGNETIC FIELDS ARE MEASURED WITH WHAT UNIT(s)

TESLA (T) or GAUSS (G)

1 Tesla equals 10,000 Gauss

ELECTROMAGNETISM

Electrons that flow through a wire with current produce a magnetic field about that wire represented by magnetic field lines.

HOW ARE MAGNETIC FIELDS MADE STRONGER?

Bending or looping the wires so that the magnetic field lines overlap inside the loop, where they come together and becoming stronger.

STACKING THE LOOPS ON TOP OF ONE ANOTHER

Makes the magnetic field run through the center

SOLENOID

A coil of wire with current. The magnetic field of the solenoid is concentrated through the center of the coil.

ELECTROMAGNET

Solenoid wrapped around a ferromagnetic material such as ironwill further intensify the magnetic field. Changing the current changes the magnets intensity.

(CURRENT IS DRIVING MAGNETIC FIELD!)

WHAT DOES ELECTROMAGNET DEMONSTRATE?

That electricity can produce a magnetic field a stationary magnet cannot

WHAT IF THE MAGNET MOVES?

If it moves there is current, the physical motion causes the magnetic field to move, and so creating a magnetic field nearthe coil of wire.

FARADAYS LAW

"An electric current is induced in a circuit if some part of that circuit is in a changing magnetic field. "

MAGNITUDE OF THE INDUCED CURRENT DEPENDS ON FOUR FACTORS:

1. Strength of magnetic field.

2. Velocity of magnetic field as it moves past the conductor.

3. The angle of the conductor to the magnetic field.

4. The number of turns in the conductor.

•both dipoles have to be perpendicular to solenoid.

ELECTRIC GENERATOR

The coil wire is placed between two poles of a strong magnetic field. The coil is rotated by mechanical energy causes current to be generated in the solenoid. Efficiency is affected with friction and heat lost by resistance in electrical components.

•changes mechanical energy to electrical energy

MOTORS

Principle of using electric current to produce mechanical motion.

INDUCTION

Process of electrical fields acting on one another without contact.

INDUCTION MOTOR

Used with x-ray tubes to make the anode rotate. The rotor within the vacuum tube to turn without applying electricity directly to the rotor.

INDUCTION MOTOR PARTS AND FLOW

•ROTOR: copper and iron

•STATOR: ring of electromagnets around the rotor.

•current goes to each pair of stators sequentially and induces current flow in the rotor which in turn creates a magnetic field.

RPM'S

Revolutions per min. 10,000 RPMs created in x-ray tube. Increase number of electromagnets to increase RPMs

TRANSFORMERS

Change or transform the intensity of alternating voltage and therefore current.

used in x-ray to transform incoming voltage of 110v to 220v and then to KV in x-ray

•to change voltage you must change current because of OHMS LAW

STEP UP TRANSFORMER

•Has more windings on the secondary coil.

•it will increase voltage from the primary coil.

•used in x-ray.

Primary coul smaller than secondary coil.

STEP DOWN TRANSFORMER

•has fewer windings on the secondary coil.

•ised to decrease incoming voltage.

• used when transmitting electricity from power poles to a house.

Primary coil has more windingsthan secondary coil and is leas effective.

VOLTAGE GOES UP THEN CURRENT GOES

Voltage goes up then current goes down.

TRANSFORMER LAW

V2/V1=N2/N1

•because p=IV there is an inverse relationship between change in current and change in voltage.

•in step up transformer, voltage increases while amperage decreases.

•in a step down transformer, voltage decreases while amperage increases.

I2/I1=N1/N2 and

I2/I1=V1/V2

CLOSED CORE TRANSFORMER

Layers of iron that are laminated reduces energy loss.

AUTOTRANSFORMERS

Uses one winding only. Allows the amount of voltage accessed to vary by tapping into the desired voltage.

SHELL TYPE TRANSFORMER

Both primary and secondary coils are insulated and wrapped on top of each other which minimizes physical distance and increases induction efficiency.

-magnetic field lines are more concentrated to the center of the shell.

-inverse square law of magnetism.

•MOST COMMONLY USED TRANSFORMER TYPE

X-RAY IMAGING SYSTEMS THREE COMPONENTS ARE

X-ray tube, operating console and high voltage generator

XRAY EXAM TABLE MUST BE

Radiolucent with uniform thickness non fluoro tables move up and down and has bucky tray with AEC device and reciprocating grid.

FLUOROSCOPY TABLE

Tilt, 90 degrees towards feet and approximately 30 degrees trendelenburg

LEAD WINDOW AS WELL AS WALL CREATE

Secondary barrier

OPERATING CONSOLES ALLOW WHAT?

Manipulation of KVP and mAs, focal spot, bucky selector and AEC control. May have APR as well with preprogrammed techniques that are suggestions.

WHAT IS RADIATION QUANTITY AND QUALITY?

Radiation quantity describes number of xrays in beam aka intensity of xray beam manipulated via mA.

Radiation quality describes penetrability of xray beam manipulated via KVP.

INCOMING VOLTAGE MAY VARY BY HOW MUCH?

Incoming voltage varies by 5% from required 220v. ( if voltage varies xray output varies.

LINE MONITOR

Monitors incoming voltage to xray circuit and is checking for non-fluctuating 220 v

LINE COMPENSATOR

Makes adjustments as needed to ensure voltage is a steady 220v.