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Eletromagnetism
| Question | Answer |
|---|---|
| Magnetism | is a physical property that we cannot sense |
| a proton in motion | is capable of creating a magnetic field |
| N pole point to S pole of other | if 2 bar magnets, suspended in space, were brought together, what would happen |
| a permanent magnet | a lodestone is an example of |
| an artificial permanent magnet | alnico is used in |
| Iron | classified as ferromagnetic material |
| repel, attract | if 2 magnets are brought together, N to N poles will _____, whereas N to S poles will _____. |
| most magnets | are affected by another magnetic field |
| most magnetic materials | retain their magnetic property when broken |
| a navigational compass | has both a N & S pole |
| Paramagnetism | classification of magnetism |
| at the poles | the earth's magnetic field is strongest |
| laws of magnetism | have a similar formulation as Coulomb's law of electrostatics |
| the forces b/t the poles of 2 different magnets | depends on the permeability of matter separation the magnets |
| physical laws of magnetism | require that there be a S pole for ever N pole |
| both obey the inverse square law | magnetism has some properties similar to those of electrostatics |
| Magnetism | is present in some naturally occuring ores |
| induced perpendicular to the particle motion | when a charged particle moves in a stright line, a magnetic field is |
| Align | when iron is fabricated into a magnet, magnetic domains |
| attracted to the iron | when iron is brought near a permanent magnet, the lines of the magnetic field are |
| principal classication of magnets | naturally occuring; electro-; artifically induced permanent |
| Gravity | the physical laws of magnetism are similar to the laws of ___ |
| Magnetism | cannot be felt or sensed |
| a magnetic field | exists in atoms with odd numbers of electrons in any shell |
| magnetic domain is created | when a large number of atomic magnets come together with their dipoles aligned |
| ferromagnetic material | the magnetic dipoles are randomly oriented; dipoles lose their randomness when exposed to an external magnetic field |
| permanent magnets | are artificially produced by charging them in the field of an electromagnet |
| dimagnetic materials | are unaffected by a magnetic field; examples - wood, glass, plastic |
| Alnico | is a combination of aluminum, nickel & cobalt; is 1 of the more useful magnets produced from ferromagnetic material; can be permanently magnetized |
| Electromagnets | wire around an iron core. When electric current is conducted through the wire, a magnetic field is created |
| 1 tesla (T)=10,000 gauss (G) | SI unit for magnetic flux (T)= |
| charged particle moves | a magnetic field is induced perpendicular to the particle motion |
| a hydrogen nucleus | has an associated magnetic field |
| electrons in motion | known as electricity or electromagnetism |
| EMF | is expressed in units of volts |
| Oersted | the experimental link connecting electric & magnetic forces was discovered by: |
| a battery | is a source of electromotive force |
| Intensity | the principal advantage of an electromagnet over a solenoid is magnetic field |
| faraday's law | an electric current will flow if the conductor is in a changing magnetic field |
| electric current | the term electromagnetic induction refers to the production of |
| magnetic field | electromagnet & bar magnet produce what type of similar field |
| a changing magnetic field is present | given a closed loop of wire with no electron flow, an electric current can be induced if |
| mutual 2 coils / self 1 coil | the principal difference b/t self-induction and mutual induction is that: |
| changes direction | when an AC source is connected to a coil the current flow through the magnetic field |
| 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 |
| a coil of wire will | conduct DC relatively unimpeded |
| in the secondary coil | when an electric current is induced by mutual induction, such current flows: |
| Generator | an electromechanical device |
| magnetic field produced | in a transformer is based on mutual induction |
| source of EMF | 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 |
| in a transformer is based on mutual induction | |
| source of EMF | |
| 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 |
Created by:
Sassyconch
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