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31 Cards in this Set
- Front
- Back
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electrical current
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flow of electricty
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electrical pressure
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causes the current to flow
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electrical resistance
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regulates the flow of current
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coulombs
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a measure of the quantity of electricity
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ampere
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one coulomb per second
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voltage
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pressure (difference in potential, drop in potential, or a drop between two points
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ohm
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electrical resistance
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volts
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represent the pressure causing it to flow
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ohms law
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V/IxR (cover the unknown)
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Watt
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draws one ampere when one volt is applied
P(power in watts)=V(volts)x I(amperes) |
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Measuring electrical current
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insert a current reader into the circut
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ammetere
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measures an electric current and is read in amperes
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Measuring electrical power
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use a voltmeter (same as ammetere but does not become part of the circut)
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Measuring electrical resistance
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divide voltmeter by the ammeter reading, or an ohmmeter (megger) is used
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rheostat
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absorbs electrical energy
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Heating effect
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wire is large, current is small, heat is little but if wire is small and current is large, it becomes quite hot
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magnetic effect
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a wire carrying a current of electricty deflects a magnetic needle. when the wire is insulated and coied around iron, the current magnetizes the core
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chemical effect
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current is capable of decomposing certain cheical compunds
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physiological effect
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if current passes though a body, it produces muscle contractions
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dynamo
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machines that6 conv ert either mechanical energy into eledctrial energy or vise versa
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generator
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when mechanical energy supplied in the form of rotation is converted into electrical energy.
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motor
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when electical energy is converted into mechanical energy
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direct or continous current
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flows in the same direction and has a constant strenght for definite periods of time
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pulsating current
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has a uniform direction, and the current strenght varies
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alternating current
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changes directions at regulated times. During an interval, the current rises then falls smoothly.
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Kilohertz (KHz)
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a thousand Hz
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Megahertz (MGz)
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a million HZ
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impedance
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total resistances and reactances in an ac circuit
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recitfiers
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used to change alernating current into direct current
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NPN transistor
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consists of P type material sandwiched between two N type sections
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PNP
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Ntype material sandwiched between two P type material.
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