Eletromagnetism
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| Magnetism | is a physical property that we cannot sense
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| a proton in motion | is capable of creating a magnetic field
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| N pole point to S pole of other | if 2 bar magnets, suspended in space, were brought together, what would happen
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| a permanent magnet | a lodestone is an example of
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| an artificial permanent magnet | alnico is used in
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| Iron | classified as ferromagnetic material
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| repel, attract | if 2 magnets are brought together, N to N poles will _____, whereas N to S poles will _____.
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| most magnets | are affected by another magnetic field
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| most magnetic materials | retain their magnetic property when broken
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| a navigational compass | has both a N & S pole
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| Paramagnetism | classification of magnetism
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| at the poles | the earth's magnetic field is strongest
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| laws of magnetism | have a similar formulation as Coulomb's law of electrostatics
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| the forces b/t the poles of 2 different magnets | depends on the permeability of matter separation the magnets
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| physical laws of magnetism | require that there be a S pole for ever N pole
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| both obey the inverse square law | magnetism has some properties similar to those of electrostatics
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| Magnetism | is present in some naturally occuring ores
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| induced perpendicular to the particle motion | when a charged particle moves in a stright line, a magnetic field is
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| Align | when iron is fabricated into a magnet, magnetic domains
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| attracted to the iron | when iron is brought near a permanent magnet, the lines of the magnetic field are
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| principal classication of magnets | naturally occuring; electro-; artifically induced permanent
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| Gravity | the physical laws of magnetism are similar to the laws of ___
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| Magnetism | cannot be felt or sensed
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| a magnetic field | exists in atoms with odd numbers of electrons in any shell
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| magnetic domain is created | when a large number of atomic magnets come together with their dipoles aligned
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| ferromagnetic material | the magnetic dipoles are randomly oriented; dipoles lose their randomness when exposed to an external magnetic field
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| permanent magnets | are artificially produced by charging them in the field of an electromagnet
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| dimagnetic materials | are unaffected by a magnetic field; examples - wood, glass, plastic
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| Alnico | is a combination of aluminum, nickel & cobalt; is 1 of the more useful magnets produced from ferromagnetic material; can be permanently magnetized
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| Electromagnets | wire around an iron core. When electric current is conducted through the wire, a magnetic field is created
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| 1 tesla (T)=10,000 gauss (G) | SI unit for magnetic flux (T)=
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| charged particle moves | a magnetic field is induced perpendicular to the particle motion
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| a hydrogen nucleus | has an associated magnetic field
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| electrons in motion | known as electricity or electromagnetism
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| EMF | is expressed in units of volts
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| Oersted | the experimental link connecting electric & magnetic forces was discovered by:
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| a battery | is a source of electromotive force
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| Intensity | the principal advantage of an electromagnet over a solenoid is magnetic field
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| faraday's law | an electric current will flow if the conductor is in a changing magnetic field
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| electric current | the term electromagnetic induction refers to the production of
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| magnetic field | electromagnet & bar magnet produce what type of similar field
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| a changing magnetic field is present | given a closed loop of wire with no electron flow, an electric current can be induced if
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| mutual 2 coils / self 1 coil | the principal difference b/t self-induction and mutual induction is that:
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| changes direction | when an AC source is connected to a coil the current flow through the magnetic field
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| mutual induction occure in 2nd coil | if 2 coils are positioned near each other and a varying source of EMF is passed through the 1st coil
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| a coil of wire will | conduct DC relatively unimpeded
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| in the secondary coil | when an electric current is induced by mutual induction, such current flows:
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| Generator | an electromechanical device
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| magnetic field produced | in a transformer is based on mutual induction
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| source of EMF | which of the following is not required for an electric generator?
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| the commutator ring | the main difference b/t AC and a DC electric generator is
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| alternating pos (+) & neg (-) intensity | the electric current produced by an AC generator has:
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| pulsating & in 1 direction | the electric current intensity produced by a DC generator is
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| source of EMF | one difference b/t an electric generator & an electric motor is the
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| Switch | in electric generators & motors the commuator ring acts as a
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| rotate the anode | an induction motor is used in an x-ray machine to
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| strength, velocity, angle, # of turns | the magnitude of induced current in Faraday's experiment depends on 4 factors
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| mutual & self induction | name the 2 laws of electromagnetics (Faraday's Laws)
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| mutual induction | 2 coils placed close together & the 1st coil is supplied with a varying or AC current causes a flow in the 2nd coil. Primary coil - 1st coil; seconday coil - is the coil induced from the 1st coil alternating current (AC)
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| self induction | induction of an opposing EMF in a coil by its own varying magnetic field from AC
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| secondary voltage | in the relationship b/t primary & seconday voltage in a step-up transformer which is greater?
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| I2R loss; hysteresis loss; eddy current loss | 3 principle casues for transformer energy losses
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| I2R loss | aka copper loss; caused by inherent resistance to current flow that is found in all conduction; proportional to square of current; minimized by using low-resistnace
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| hysteresis loss | lagging loss; demagnetizes & remagnetizes the core material; coercivity is the characteristic that requires engergy to carry out this constant reorientation of the magnetic dipoles
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| eddy current loss | currents opposing the cause which produced them; laminating the transformer core reduces this loss
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| diff b/t AC & DC | can be seen by converting the AC (alternating current) to DC (direct current) by replacing the slip rings on an Ac current with a simple device called the communtator ring, which acts like a switch, thus changing the polarity of the contact on the brush w
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| magnetic field | transformers have iron cores in order to intensify the
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| the transformer | changes electrical potential & current into higher or lower intensities
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| Voltage | a transformer "transforms" or changes electric:
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| step-up transformer | a trnsformer with a tuns ratio greater than I is:
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| closed-core | the transformer that resembles a square donut is called an ____ transformer.
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| turns ratio is | secondary windings / primary windings
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| Autotransformer | contains a single winding to serve as both primary & secondary coils
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| magnetic field produced | if DC is applied to the primary coil of a transformer
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| rectifier |
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| converts AC to DC |
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| thermionic emission refers to | electron emission from a heated source
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| filament |
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| is a component of a tube-type of rectifier |
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| tube rectifier/vacuum-tube diode, electron flow is | from cathode to anode only when the anode is connected to a positive voltage with respect tot eh cathode
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| circuit containing a solid-state diode | electrons will be permitted to flow in one direction but not the other
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| Magnetism | is one of the fundamental forces. When a charged particle is in motion a magnetic force field perpendicular to the motion will be created.
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| Electromagnets | is a temporary magnet produced by a moving electric current
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| diff b/t electron flow & conventional current flow |
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| electron flow is actually from negative to positive poles while conventional electric current is described as going from positive to negative poles. |
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| thumb pointing | movement of conductor
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| index finger | magnetic lines of force field
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| middle/other finger | current or electron flow
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| 3 ways induce electromagnetic current flow in a conductor | 1- move the conductor through a stationary, unchanging-strength magnetic field; 2- move magnetic lines of force through a stationary conduction with an unchanging-strenght magnetic fiels; 3- vary the magnetic flux strength from a stationary magnet through
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| 4 factor controlling strength of electromagnetically induced current | 1- the strength of the magnetic field; 2- the speed of the motion b/t lines of force & conductor; 3- the angle b/t the magnetic lines of force & the conductor; 4- the number of turns in the conduction coil
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| diff generator & motor | generator converts mechanical energy to electrical energy & a motor converts electrical energy to mechanical energy. (if the power goes out we can use a generator (mechanical) to have lights (electricity); motor battery (electrical) to start motor (mechan
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| function of a transformer | a divice that operates on alternating current to change electricity from a primary voltage to a secondary source. It utilizes the principles of electromagnetic mutual induction with the application of Ohm's Law.
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| transformer law | Vs/Vp = Ns/Np; V= potential difference in volts; N= # of turnes of wire in the coil; p= primary coil; s=secondary coil
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| Autotransformer | used to vary the incoming line voltage to an appropriate level for the high voltage step-up transformer.
🗑
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| Diode | creates an electrical "one way street" by permitting electrons to flow easily in 1 direction while offering a high resistance to movement in the other direction.
🗑
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| Rectification | the process by which alternating current is changed to pulsating direct current
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| componets for full-wave rectified circuit | 4 rectifiers in a bridge circuit are necessary
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| in a transformer is based on mutual induction |
🗑
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| source of EMF |
🗑
|
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| which of the following is not required for an electric generator? |
🗑
|
||||
| the commutator ring |
🗑
|
||||
| the main difference b/t AC and a DC electric generator is |
🗑
|
||||
| alternating pos (+) & neg (-) intensity |
🗑
|
||||
| the electric current produced by an AC generator has: |
🗑
|
||||
| pulsating & in 1 direction |
🗑
|
||||
| the electric current intensity produced by a DC generator is |
🗑
|
||||
| source of EMF |
🗑
|
||||
| one difference b/t an electric generator & an electric motor is the |
🗑
|
||||
| Switch |
🗑
|
||||
| in electric generators & motors the commuator ring acts as a |
🗑
|
||||
| rotate the anode |
🗑
|
||||
| an induction motor is used in an x-ray machine to |
🗑
|
||||
| strength, velocity, angle, # of turns |
🗑
|
||||
| the magnitude of induced current in Faraday's experiment depends on 4 factors |
🗑
|
||||
| mutual & self induction |
🗑
|
||||
| name the 2 laws of electromagnetics (Faraday's Laws) |
🗑
|
||||
| mutual induction |
🗑
|
||||
| 2 coils placed close together & the 1st coil is supplied with a varying or AC current causes a flow in the 2nd coil. Primary coil - 1st coil; seconday coil - is the coil induced from the 1st coil alternating current (AC) |
🗑
|
||||
| self induction |
🗑
|
||||
| induction of an opposing EMF in a coil by its own varying magnetic field from AC |
🗑
|
||||
| secondary voltage |
🗑
|
||||
| in the relationship b/t primary & seconday voltage in a step-up transformer which is greater? |
🗑
|
||||
| I2R loss; hysteresis loss; eddy current loss |
🗑
|
||||
| 3 principle casues for transformer energy losses |
🗑
|
||||
| I2R loss |
🗑
|
||||
| aka copper loss; caused by inherent resistance to current flow that is found in all conduction; proportional to square of current; minimized by using low-resistnace |
🗑
|
||||
| hysteresis loss |
🗑
|
||||
| lagging loss; demagnetizes & remagnetizes the core material; coercivity is the characteristic that requires engergy to carry out this constant reorientation of the magnetic dipoles |
🗑
|
||||
| eddy current loss |
🗑
|
||||
| currents opposing the cause which produced them; laminating the transformer core reduces this loss |
🗑
|
||||
| diff b/t AC & DC |
🗑
|
||||
| can be seen by converting the AC (alternating current) to DC (direct current) by replacing the slip rings on an Ac current with a simple device called the communtator ring, which acts like a switch, thus changing the polarity of the contact on the brush w |
🗑
|
||||
| magnetic field |
🗑
|
||||
| transformers have iron cores in order to intensify the |
🗑
|
||||
| the transformer |
🗑
|
||||
| changes electrical potential & current into higher or lower intensities |
🗑
|
||||
| Voltage |
🗑
|
||||
| a transformer "transforms" or changes electric: |
🗑
|
||||
| step-up transformer |
🗑
|
||||
| a trnsformer with a tuns ratio greater than I is: |
🗑
|
||||
| closed-core |
🗑
|
||||
| the transformer that resembles a square donut is called an ____ transformer. |
🗑
|
||||
| turns ratio is |
🗑
|
||||
| secondary windings / primary windings |
🗑
|
||||
| Autotransformer |
🗑
|
||||
| contains a single winding to serve as both primary & secondary coils |
🗑
|
||||
| magnetic field produced |
🗑
|
||||
| if DC is applied to the primary coil of a transformer |
🗑
|
||||
| rectifier |
🗑
|
||||
| converts AC to DC |
🗑
|
||||
| thermionic emission refers to |
🗑
|
||||
| electron emission from a heated source |
🗑
|
||||
| filament |
🗑
|
||||
| is a component of a tube-type of rectifier |
🗑
|
||||
| tube rectifier/vacuum-tube diode, electron flow is |
🗑
|
||||
| from cathode to anode only when the anode is connected to a positive voltage with respect tot eh cathode |
🗑
|
||||
| circuit containing a solid-state diode |
🗑
|
||||
| electrons will be permitted to flow in one direction but not the other |
🗑
|
||||
| Magnetism |
🗑
|
||||
| is one of the fundamental forces. When a charged particle is in motion a magnetic force field perpendicular to the motion will be created. |
🗑
|
||||
| Electromagnets |
🗑
|
||||
| is a temporary magnet produced by a moving electric current |
🗑
|
||||
| diff b/t electron flow & conventional current flow |
🗑
|
||||
| electron flow is actually from negative to positive poles while conventional electric current is described as going from positive to negative poles. |
🗑
|
||||
| thumb pointing |
🗑
|
||||
| movement of conductor |
🗑
|
||||
| index finger |
🗑
|
||||
| magnetic lines of force field |
🗑
|
||||
| middle/other finger |
🗑
|
||||
| current or electron flow |
🗑
|
||||
| 3 ways induce electromagnetic current flow in a conductor |
🗑
|
||||
| 1- move the conductor through a stationary, unchanging-strength magnetic field; 2- move magnetic lines of force through a stationary conduction with an unchanging-strenght magnetic fiels; 3- vary the magnetic flux strength from a stationary magnet through |
🗑
|
||||
| 4 factor controlling strength of electromagnetically induced current |
🗑
|
||||
| 1- the strength of the magnetic field; 2- the speed of the motion b/t lines of force & conductor; 3- the angle b/t the magnetic lines of force & the conductor; 4- the number of turns in the conduction coil |
🗑
|
||||
| diff generator & motor |
🗑
|
||||
| generator converts mechanical energy to electrical energy & a motor converts electrical energy to mechanical energy. (if the power goes out we can use a generator (mechanical) to have lights (electricity); motor battery (electrical) to start motor (mechan |
🗑
|
||||
| function of a transformer |
🗑
|
||||
| a divice that operates on alternating current to change electricity from a primary voltage to a secondary source. It utilizes the principles of electromagnetic mutual induction with the application of Ohm's Law. |
🗑
|
||||
| transformer law |
🗑
|
||||
| Vs/Vp = Ns/Np; V= potential difference in volts; N= # of turnes of wire in the coil; p= primary coil; s=secondary coil |
🗑
|
||||
| Autotransformer |
🗑
|
||||
| used to vary the incoming line voltage to an appropriate level for the high voltage step-up transformer. |
🗑
|
||||
| Diode |
🗑
|
||||
| creates an electrical "one way street" by permitting electrons to flow easily in 1 direction while offering a high resistance to movement in the other direction. |
🗑
|
||||
| Rectification |
🗑
|
||||
| the process by which alternating current is changed to pulsating direct current |
🗑
|
||||
| componets for full-wave rectified circuit |
🗑
|
||||
| 4 rectifiers in a bridge circuit are necessary |
🗑
|
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