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75 Cards in this Set
- Front
- Back
• the study of stationary electric charges • the study of the distribution of fixed charges |
electrostatics |
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fundamental unit of electric charge |
(SI): coulomb (c) |
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measured in volt (V) |
electric potential |
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potential energy per unit charge |
volt (1 V = 1 J/C) |
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measured in ampere (A) |
electric current (I) |
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one coulomb of electric charge flowing per second |
ampere (1 A = 1 C/s) |
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transfer or movement of electron from one object to another object |
electrification |
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electrification is created by what |
• friction • contact • induction |
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when one object is rubbed against another |
friction |
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when two objects touch, permitting electrons to move from one to the other |
contact |
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the process of electric fields acting on another without contact (most important method used in the operation of electronic devices) |
induction |
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if one object has too few or too many electrons |
electrified |
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the object that behaves as a reservoir for stray electric charges |
electric ground |
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the lines of force that causes charged particles to move from one pole to another |
electric field |
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points outward |
positive charge |
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points toward |
negative charge |
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unlike charges attract, like charges repel |
repulsion-attraction |
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states that the electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects. |
coulomb's law |
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equation form of coulomb's law |
F = k•Q1•Q2 / d² |
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do not have electric field |
uncharged particles |
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charges uniformly distributed at the surface |
distribution |
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the force between two charges. • directly proportional to the product of their magnitudes • inversely proportional to the square of distance between them |
inverse square law |
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only negative charges move along the solid conductors |
movement |
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what are tightly bound inside the nucleus? |
protons |
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the study of electric charges in motion |
electrodynamics |
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movement of electrons along the wire |
electric current |
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what are the two types of current |
direct current and alternating current |
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electrons that flow in only one direction |
direct current |
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waveform of direct current |
straight line |
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electrons that flow alternately in opposite direction |
alternating current |
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waveform of alternating current |
sinusoidal |
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what are the four magnetic states of matter |
conductor, insulator, semiconductor, superconductor |
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any substance through which electrons flow easily. example: copper, aluminum, water |
conductor |
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variable resistance, obeys ohm's law, and requires voltage |
conductor |
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any material that does not allow electron flow. example: glass, rubber, clay |
insulator |
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does not permit electron flow, extremely high resistance, and necessary with high voltage |
insulator |
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a material that in some condition behaves as an insulator and as a conductor. example: silicon, germanium |
semiconductor |
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can be conductive, can be resistive, basis for computers |
semiconductor |
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any material that allows electrons to flow without resistance. example: niobium, titanium |
superconductor |
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no resistance to electron flow, no electric potential required, must be very cold |
superconductor |
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a pathway that permits electrons to move in a complete circle from their source through the various components and back again |
electric circuits |
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take note |
more complex > the greater the resistance > decrease electric current |
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the voltage across the total circuit or any portion of the circuit is equal to the current times the resistance |
ohm's law |
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formula for ohm's law |
V = I • R (voltage) R = V / I (resistance) I = V / R (current) |
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2 basic types of electric circuit |
series circuit and parallel circuit |
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elements are connected at their ends rather than lying in a line along a conductor |
parallel circuit |
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all circuit elements are connected in a line along the same conductor |
series circuit |
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inhibits flow of electrons |
resistor |
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provides electric potential |
battery |
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momentarily stores electric charge |
capacitor |
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increases or decreases voltage by fixed amount (AC only) |
transformer |
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allows electrons to flow in only one direction |
diode |
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• it is measured in watts (W) • 1 W: 1 A (current) x 1 V (voltage) |
electric power |
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formulas for electric power |
• P = IV • P = I²R (for power losses) |
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• fundamental property of forms of matter • it has no smallest unit |
magnetism |
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• any material that produce magnetic field • has north and south pole |
magnets |
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magnets thay have two poles |
• bipolar/dipolar |
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two scientists that did an experiment about electromagnetic induction |
michael faraday and hans oersted |
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• changing magnetic field induces current • magnetic field generates electricity • ammeter: measures current |
michael faraday's experiment |
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measures current |
ammeter |
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• moving or spinning charges induces magnetic field • electricity generates magnetic field |
hans oersted experiment |
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any charged particle in motion creates a magnetic field |
magnetism |
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types of magnets |
• natural magnet (ex. lodestone) • artificial permanent magnet (ex. compass) • electromagnets |
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four magnetic states of matter |
• nonmagnetic - unaffected ex. wood & glass • diamagnetic - weakly repelled ex. water & plastic • paramagnetic - weakly attracted ex. gadolinium • ferromagnetic - strongly magnetized ex. iron, nickel & cobalt |
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• like magnetic poles repel • unlike magnetic poles attract |
magnetic laws |
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• Imaginary lines ofmagnetic field enterthe south pole• Imaginary lines ofmagnetic field leavethe north pole |
magnetic laws |
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• An electric current is induced in a circuit if some part of that circuit is in a changing magnetic field• Faraday and Oersted Experiment |
electromagnetic induction |
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• He observed the currentin a changing magneticfield • He described the first lawof electromagneticinduction |
michael faraday |
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• He demonstrated thatelectricity can be used togenerate magnetic fields |
hans oersted |
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The magnitude of the induced current depends on four factors:1. The strength of the magnetic field2. The velocity of the magnetic field as it moves pas the conductor3. The angle of the conductor to themagnetic field4. The number of turns in the conductor |
faraday's law |
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mechanical motion produces electric current |
electric generator |
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• it changes the intensity of alternating voltage and current • applicable only on AC |
transformer |
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• turns ratio greater than 1 • Ns > Np • Vs > Vp • Is < Ip |
step up transformer |
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• voltage and number of turns are directly proportional • formula: Vs/Vp = Ns/Np |
transformer law |
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• current is inversely related to the number of turns and voltage • formulas: Is/Ip = Np/Ns Is/Ip = Vp/Vs |
transformer law on current |