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Connie Unit dos

Electrical stuff

QuestionAnswer
What is the phenomena associated w/ stationary and moving positive and negative charges? Electricity
Two types of electricity: 1. current electricity2. static electricity
Electricity in motion (dynamic charges) current electricity
Electricity at rest (stationary charges) Static electricity
What is the study of stationary electric charges? Electrostatics
The unit used to measure a static charge is called the ? Coloumb (C) named after Charles Coloumb.
The Coloumb (C) is a fixed (constant) number of positive or negative charges and is equal to ? 1 C = 6.3 x 10^18 charges
the process of applying a positive or negative charge to a neutral object through the transfer of electrons. Electrification
To make a neutral object become negative, are electrons added or removed from the object? Added
To make a neutral object positive, are electrons added or removed from the object? Removed
Surrounding every charged object is an ? Electrostatic field
The electrostatic field has ?? as the charge on the object producing the field. The same
What determines the area of the field? The intensity (quantity) of the charge.
What will produce a large field, a small or big charge? The greater the charge, the bigger the field.
The planet Earth is considered to be an infinite ? for electrons. Resorvoir
An object is said to be grounded when it is ? connected to the ground using a material that will permit e- to easily move between the earth and the object Physically
What is the primary goal for grounding throughout any facility? Safety
What is the secondary goal for grounding? Effective Lightning Protection
An object that is said to be positive has a ? of electrons. Deficiency
What is the path flow of electrons if a positive object is electricall grounded to the earth? Electrons will move FROM the earth into the positive object until it is neutralized.
An object that is negative has too few or too many electrons? It is said to have too many.(an excess of e-)
What is the path flow of electrons if a negative egative object is electrically grounded to the earth? Electrons will move from the negative object into the Earth until the object is neutralized.
Electrically connecting any charged object to the Earth(grounding) will ?? the object. Instantly neutralize
Electrical symbol for ground ( arrow pointing down)
Electrostatic Law #1 Like charges repelunlike charges attract
Electrostatic law #2 states that electric charges reside where on a a charged object? On the external surface
The force between two charges is ? ? to the product of their magnitudes and ?? to the square of the distance between them. directly proportional/inversely proportional
Alternating current describes current that continuously ? direction as it moves through a substance. changes
Direct current describes a current that moves through a substance in the ? direction. Same
Which charges can move through all states of matter? (solids, gases, and liquids? Negative
Which charges can only move through liquids, and gases? Positive charges
As current electricity moves through matter, charges enounter ? w/ each other and atoms of matter itself. Friction
Friction is also known as Resistance
Electrical charges will always follow the path of ? resistance Least
Any substance which permits electrical charges to move very easily through that substance. (very low resistance) Conductor
gold, silver, copper, aluminum are examples of... Conductors
Any substance that blocks the flow of charges through the substance. (very high resistance) describes: Insulator
glass, rubber, plastic, wood are examples of: Insulators
Substances that act as conductors under certain conditions and as an insulator under other conditions describes: Semiconductors
germanium, silicon are known as: semiconductors
Superconductors are substances that have blank resistance when operated at extremely low temp. Superconductors
Nobium and Titanium are known as: superconductors
Electricity that moves from positive to negative describes: Concept of conventional flow
Electricity that moves from electric to positive describes: Concept of electron flow
Electrician follow which concept of flow? Conventional flow
Radiographers follow which concept of flow? Electron flow
When one electron is inserted into one end of the conductor... the electrons move forward until one electron is ejected on the other end.
The source for external electrons is... Power Supply
the electron that is displaced from the conductor carries what type of energy? Kinetic
What causes the electrons to move in the conductor? A difference in poetential energy must exist between two locations to make current.
The force created between two locations (Potential energy difference) in the conductor is called the: Electromotive force
Potential energy difference, electromotive force and ? are all synonymous. Voltage
EMF causes the electrons to move from the area of ? concentration toward the area of ? concentration. Higher to lower. (more negative to less negative)
The movement will continue until a ? is established throughout the substance. Equilibrium of charge concentration
Unit of electromotive force is called the: Volt
The number of electrons passing a given point per unit of time is a measure called: Current Intensity
Current Intensity is called the: Ampere
One ampere equals: One coulomb of charge moving past a point per second. 6.3x10^18 charges
The inherent action which opposes the forward movement of current describes: Resistance
The unit of electrical resistance is: Ohm
Resistance due to the characteristic electrical conductor material itself: Inherent resistance
Factors affecting inherent resistance Length of conductor, Cross sectional area of the conductor, What the conductor is made of, Temp of conductor during current movement.
What is the relationship of the length of the conductor to its inherent resistance Directly proportional (the longer the conductor, the more resistance)
What is the relationshiip of the cross sectional area to its' inherent resistance They're inversely proportional (The bigger the cross sectional area, the less the resistance)
Elements with what type of valence and how many shells will have a lower resistance? A valence of +1 and more shells Gold vs. silver vs. Copper
As the temperature increases the inherent resistance: Increases
what is a fixed resistance? Resistor
What is a variable resistance? Rheostat
Resistor symbol Fixed amount of resistance
Rheostat symbol Variable amount of resistance
Added resistance in a conductor is called a ? Load
The purpose for any electric circuit is ? To create power to do work
Electric power is the product of ? Current Intensity and electromotive force
The formula of power= P = I x V
Unit of measurement for electric power is: Watt
Electric circuit is a closed complete ? pathway through whhich current can move. conductive
Minimum circuit requirements: Closed conductive pathpower supplyloadon-off switch
What are the four types of circuits: series, parallel, complex, short
Which three are functioning ciruits? Series, parallel, complex
A series circuit provides only ? pathway to follow and where ? is constant at all locations throughout the circuit. Pathway, amperage
Parallel Circuit provides more than one pathway for current to follow and where ? is constant across all pathways. Voltage
If a circuit contains some loads that are in a series and others that are in a parallel the circuit is called ? A complex circuit
If the total electrons that move through one load are the same amount of electrons that move through another load than the two loads are said to be In series
If the total e- move through one load are not the same e- that move through another load than the two loads are said to be in Parallel
A short circuit that contains ??? causes excessive heat to build within the circuit. Insufficient added resistance
What has to be properly balanced for the circuit to operate correctly and safely? Current Intensity (amp),electromotive force (volt), and resistance (ohm).
The balance is determined by what law? Ohms law
Ohm's law states: Current intensity is directly proportional to electromotive force and inversely proportional to resistance
what are the variations of ohms law? I=V/R V=IR R=V/I
Ohm's law sates the relationship between? Current and voltage and resistance
Watt's law states the relationships of: Power, and current and voltage and resistance.
Watts formula: P=IV I=P/V V=P/I (pivvir)
What are the four effects of electric current? Luminous effect thermal effectMagnetic effect Chemical
which effects always occur? Magnetic and thermal effect.
When a current is passed through a resistance, friction occurs that produces heat Thermal effect
Power loss (heat production) formula P=I^2R
Chemical Effect: Placing certain chemicals b/n two electrical points (electrodes) will cause a reaction producing emf and current flow
Types of batteries: Dry cell and Wet cell
Dry cell battery has a moist chemical paste b/n two electrodes which creates chem. reaction and producing and emf of how many volts per cell? 1.5 volts
Wet cell battery has a liquid between two electrodes creates chem reaction to produce an emf of how many volts per cell? 2.0 volts
Devices used to measure electrical current characteristics: Ciruit meters
Anmeter measures amperage
Voltmeter voltage
Battery symbol 1 cell 2 cells 4 cells
The ability of certain materials to attract iron: Magntism
Any material that can attract a piece of ? describes a magnet. Iron
Process whereby a certain material becomes a magnet Magnetization
How many years ago when the magnetic phenomena was first observed? 3000 years ago
where was it first discovered? Present day Turkey (then called Magnesia)
The ore that was discovered was named Magnetite
Magnetite is now called: Lodestone
What was the first true scientific device on record that operated under the principles of magnetism? Compass
The compass was created during what time? 1000 A.D
Who discovered that a magnet has polarity (Poles)North and south Peter Peregrinus
Who discovered that the planet Earth is one giant magnet during the 16h century? William Gilbert
Who discovered that an electric current will produce a magnetic effect in 1820? Hans Oersted
Who discovered that a magnetic effect can ve used to produce an electric current in 1835? Michael Faraday
What are the three types of magnets? Natural, artificial, and electromagnets
Natural magnet is any material that naturally exhibits the property of magnetism (not manmade) whate are the two examples? Lodestone and Earth
Artificial magnet is a manmade material that exhibits the property of magnetism. What is an example? Alnico, a strong magnet made of aluminum, nickel, and cobalt.
Electromagnet is a material that exhibits the property of magnetism only during the application of what? an electric current
What is a conductor wire shaped into a coil? Helix
When the helix is connected into a circuit so electricity moves through the coil a ? is formed? Solenoid
A solenoid is also known as an? Inductor
When a rod of iron is placed through the center of the coil of the solenoid what is formed? Electromagnet
Magnetism law #1 states that regardless of shape/size every magnet has two poles: North pOle and south pole
Magnetism law#2 states that: Like magnetic poles repel each other, unlike magnetic poles attract each other
Magnetism law #3 states that the force of attraction/repulsion between two magnetic poles are directly proportional to the product of the strengths of the poles and inversely proportional to the square of the distance between the poles
Third magnetic law is sometimes called the: Law of Gauss
Surrounding every magnetic is a field magnetic energy composed of lines of force called maagnetic flux
the first flux property states that flux exits the North pole and enters the south pole
If some flux travel too far from the magnet w/ insufficient energy to return to the magnet it results in a loss of magnetism Flux leakage
the 2nd flux property states that flux form closed loops "magnetic circuits" and the flux lines from the same magnet never? cross over each other
Flux property 3 states that flux that travel in the same direction... Repel each other and flux that travel in opposite directions attract each other
flux propety 4 states: flux can be distorted by inserting a magnetic material into the flux field.
Whenever a magnetic material moves into the field of a magnet material becomes magnetized while remaining in the field is magnetic induction
Weber's observation #1 if a mag is broken into 2 pieces each piece becomes a magnet
Weber's ob 2 If a piece of iron is hammered while lying near a magnet will become a magnet
Weber's ob 3 if a piece of iron is heated while near a mag it will become a magnet
Weber ob 4 If a piece of iron is rubbed w/ a mag repeatedly in the same direction it will become a mag
Web ob 5 gently shaking a test tube of iron fillings while near a magnet will turn the fillings into a magnet
magnetic domain theory 1 all magnetic materials are composed of atomic sized magnetics called dipoles
dipoles are the smallest unit of matter containing properties of a... magnet
A dipole is a complete magnet w/ a north and south pole with a ? surrounding it? Magnetic field
MDT 2 a magnet is formed when all dipoles are: arranged in an orderly manner
the more dipoles that are arranged in the same direction: the stronger the magnet
Dipoles with no orderly arrangement are not: magnetized
When the dipoles are arranged in an orderly manner what is acquired? Polarity
a type of dipole an ion in motion
Two movements of an orbital electron: 1. e- moves around nucleus in an orbital path2. e- spins on it's own axis as it moves toward the nucleus (orbital and axial spin)
a magnetic moment is formed when what is established around a moving ion? Magnetic field
each type of movement creates an idividual magnetic movement: Orbital magnetic momentSpin magnetic moment (axial)
Another dipole is: A proton spinning on it's own axis within a hydrogen nucleus.
As a proton spins on it's own axis what is formed? a nuclear dipole
Why are some elements magnetic while most are not magnetic? Based on the spin structure of the atom within a given element resulting in magnetic moments
What determines the magnetic properties? The number of electrons found in the valence shell of the atom
when the majority of valence e- travel in the same direction around the nucleus and spin in the same direction on their own axes The greater is the magnetic potential for that atom
Atoms with a what valence electron number have more potential to become magnetic than those with a ? number of valence e-. Odd/even
Atoms with even valence number will demonstrate what kind of magnetic properties? Pretty much none since the spin motions cancel each other
Atoms with a 7 valence e- with seven orbiting clockwise and 0 cc will display strong magnetic properties
But atoms with 7 e- with four orbiting clock and 3 orbiting cc will demonstrate some magnetic properties but weak
Magnets of same substance can demonstrate varying degrees of magnetic strength
Magnetic strength depends on: Flux intensity andFlux density
Flux intensity is the ?? of flux in the magnetic field at a given point in time total number
the greater the flux intensity The stronger the magnet
Unit of flux intensity: Weber (Wb) 1 Wb=10^8 flux lines (100,000,000)
Flux Density: The # of flux per unit of area of magnetic field. the greater the flux density the stronger is the magnet
Unit of flux density: Tesla (T) IT=1 Wb/m^2
A smaller unit of flux density is called the Gauss
1T=10,000 G 1G =1/10000 T
e.g. of flux density Planet earth: 1.0 GRefrigerator magnet= 1000 GMRI magnet 40,000 Gauss
All elements can be classified according to the way they interact with an external magnetic field
what are the four magnetic classification of matter? Ferromagnetic DiamagneticParamagnetic Dimagnetic
Ferromagnetic Material is any material that is ? attracted to a magnet Strongly
examples of ferromagnetic material are iron, cobalt, nickel
Paramagnetic material is any material that is ? attracted to a magnet? Gadolinium
Diamagnetic Material is any element which is ? repelled by a magnet weakly
examples of diamagnetic material are: Beryllium, bismuth, and lead
Dimagnetic material (non-magnetic is any element which is not affected in any way by a magnet) examples are: Plastic, wood, glass
Permability also known as: Susceptability
Permability: The easew/ which a substance can be magnetized
Retentivity: The ability of a magnet to retains it's magnetism.
Substances which are high in permeability are ? in retentivity low
examples of high permeability: soft iron
Substances which are low in permeability are ? in rentivity. high
examples of low permeability substances are: Hard steel
Formula for length of conductor and inherent resistance: L1/L2= R1/R2
The formula for cross sectional area and inherent resistance: A1/A2=R2/R1
Created by: Roentgen on 2008-09-23



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