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46 Cards in this Set
- Front
- Back
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What constitutes a capacitor? |
Two conductors seperated by an insulator. |
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What is the purpose of a capacitor?
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It stores electrical energy in eletrostatic fields. |
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Does a capacitor in an AC circuit cause the current to lead or lag the voltage? |
It causes the current to lead the voltage |
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what is the basic unit of capacitance? |
The farad. |
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Why should electroytic capacitors not be used in an AC circuit? |
They are polarized. An electrolytic capacitor will passs current of one polarity, but will block current of the opposite plarity. |
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What is meant by inductance? |
The ability to store eletrical energy in electrmagnetic fields. |
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What is the basic unit of inductance? |
The Henry. |
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What is an example of an inductor used in a magneto? |
The coil. |
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Does and inductor in an AC curcuit cause the current to lead or lag in the voltage? |
It causes the current to lag behind the voltage. |
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How can you find the polarity of an electromagnetic? |
Hold the eletromagnet in your left hand with our fingers encircling the coil in the direction electrons flow (from negatie to positive). Your thumb will point to the north pole of the electromagnet. |
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What is meant by impedance? |
THe total opposition to the flow of alternating current. It is the vector sum of resistance, capacitive reactance, and inductive reactance. |
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In what units is impedance measured? |
In ohms. |
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What are five sources of electrical energy? |
Magnetism, chemical energy, light, heat, and pressure. |
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What is the basic unit of power ina DC cicuit? |
The Watt. |
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What is meant by Kilowatt? |
1,000 watts. |
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What is meant by a Megawatt? |
1,000,000 watts. |
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What is the formula for power in a DC circuit? |
Power= Voltage times curent (P = E X I) |
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What is the relationship between mechanical and electrical power? |
1 horspower = 746 watts |
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what is meant by true power in an AC circuit? |
The product of the circuit voltage and the current that is in phase with the voltage. |
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In what units is true power expressed? |
In watts. |
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What is meant by apparent power in an AC curcuit? |
The product of the circuit voltage and the circuit current. |
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In what units is apparent power expressed? |
In volt-amps. |
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what is meant by reactive power in an AC circuit? |
The power consumed in the inducitve an capaitive reactances in an AC circuit. Reactive power is also called wattless power. |
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In what units is reactive power expressed? |
In volt-amps reactive (VAR), or kilovolt-amps reactive (KVAR) |
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What is meant by power factor in an AC circuit? |
The ratio of true power to apparent power. It is the ratio of circuit resisitance to circuit impedance. |
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Which law of electricity is the most important for an aircraft mechanic to know? |
ohm's law |
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what are the lements of ohm's law? |
Voltage E, Current I, and resistance R (volts, amps, and ohms). |
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what is voltage? |
Electrical pressure. |
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what is the basic unit of voltage? |
The volt. |
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What instrument is used to measure voltage? |
A voltmeter. |
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To measure voltage, is a voltmeter placed in a series or in parallel with the source of voltage? |
In parallel. |
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what is electrical current? |
The flow of electrons in a circuit. |
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What is the basic unit of current flow? |
The ampere (amp) |
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What part of an amp is a milliamp? |
One thousandth (0.001) of an amp. |
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What instrument is used to measure current flow? |
An ammeter. |
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What two things happen when current flows through a conductor? |
Heat is generated and a magnetic field surrounds the conductor. |
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To measure current through a component, is a an ammetere placed in a parallel or in series with the component? |
In series. |
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What is meant by resistance in an electrical circuit? |
the opposition to the flow of electrons? |
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What is the basic unit of electrical resistance? |
The ohm. |
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What is a megohm? |
One million (1,000,000) ohms. |
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What four things affect the resistance of an eletrical conductor? |
The material, the cross-sectional area, the length, and the temperature. |
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What instrument is used to measure electrcial resistance? |
An ohmmeter. |
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How can you tell the resistance of a compositon resistor? |
By a series of colored bands around one end of the resistor. |
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What is meant by contunuity in an eletrical circuit? |
The circuit is continous (or complete) when electrons can flow from one terminal of the power source to the other. |
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what instrument is used to measure continuity in an electrical circuit? |
An ohmmeter. |
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When measuring resistance of a component with an ohmmeter, should the circuit be energized? |
No, there should be no power on the circuit. |
