Term
| What constitutes a capacitor and what determines the capacitance? |
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Definition
2 conductors separated by an insulator.
capacitance is determined by area of the plates, amount of seperation between the plates, and the kind of insulating dielectric between the plates. |
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Term
| What is the purpose of a capacitor? |
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Definition
| Stores electrical energy in electrostatic fields. In an AC circuit it drops voltage and shifts the phase of current. |
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Term
| Does a capacitor cause current to lead or lag voltage in an AC circuit? |
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Definition
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Term
| Why should electrolytic capacitors not be used in AC circuits? |
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Definition
| because they are polarized and will only pass current of one polarity and block the other one. |
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Term
| What is inductance and what is it measured in? |
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Definition
Ability to store electrical energy in electomagnetic fields.
measured in HENERY |
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Term
| example of an inductor used in a magneto? |
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Definition
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Term
| Does and inductor cause the current to lead or lag the voltage? |
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Definition
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Term
| What is it meant to impedance and what is it measured in? |
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Definition
Total opposition to the flow of alternating current.
its the sum of resistance capacitive reactance and inductive reactance.
Measured in ohms |
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Term
| 5 sources of electrical energy |
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Definition
magnetism-generators and alternators
chemical energy-flashlight batterys
light-solar cells
heat-thermocoupler
pressure |
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Term
| Basic unit of power in DC circuit |
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Definition
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Term
| what is meant by Kilowatt and megawatt? |
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Definition
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Term
| formula for power in a DC circuit |
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Definition
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Term
| relationship between mechanical and electrical power. |
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Definition
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Term
| What is true power in an AC circuit? What is it expressed in? |
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Definition
product of the circuit voltage and the current that is in phase with this voltage.
Expressed in WATTS |
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Term
| What is apparent power in an AC circuit. how is it expressed? |
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Definition
Product of the circut voltage and the circuit current.
Expressed in volt-amps |
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Term
| what is reactive power in an ac circuit and how is it expressed? |
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Definition
power consumed in the inductive and capacitive reactances in an AC circuit.
expressed in volt-amps reactive or kilovolt-amps reactive |
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Term
| what is the power factor in an AC circuit? |
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Definition
ratio of true power to apparent power.
ALSO
ratio of circuit resistance to circuit impedance |
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Term
| Most important law of electricty? |
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Definition
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Term
| what elements make up Ohms Law |
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Definition
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Term
| what is voltage and what is the basic unit of voltage? |
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Definition
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Term
| What instrument is used to measure voltage? |
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Definition
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Term
| when measuring voltage is a volt meter placed in series or parallel with the source of voltage |
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Definition
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Term
| what is electrical current and whats the basic unit ? |
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Definition
flow of electrons in a circuit
basic unit is the AMP |
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Term
| what instrument is used to measure current flow? |
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Definition
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Term
| 2 things that happen when current flows through a conductor |
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Definition
| heat is generated and a magnetic field surround the conductor. |
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Term
| to meassure current is the ammeter placed in parallel or in series with the component? |
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Definition
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Term
| what is meant by resistance in an electrical circuit and whats the basic unit |
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Definition
opposition to the flow of electrons
OHMS |
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Term
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Definition
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Term
| four things that affect the resistance of an electrical conductor? |
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Definition
the material
cross sectional area
length
temperature |
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Term
| what instrument is used to measure electrical resistance? |
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Definition
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Term
| how can you tell resistance of a composition resistor? |
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Definition
| series of colored bands around one end of the resistor |
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Term
| what is meant by continuity in an electrical resistor |
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Definition
| when electrons can flow smoothly from the terminal of the power source to the other |
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Term
| what instrument measures continunity |
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Definition
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Term
| When measuring resistance should the circuit be energized? |
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Definition
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Term
| 3 things an electric cicuit must contain? |
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Definition
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Term
| three types of DC circuits |
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Definition
series
parallel
series-parallel |
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Term
| basic equation of ohms law |
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Definition
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Term
| What happens to the current in a DC circuit if the voltage is i ncreaded but the resistance remains the same? |
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Definition
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Term
| what happens to the current in a conductor if the length of the conductor is doubled with all other parameters unchanged. |
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Definition
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Term
| what is meant by the capacity rating of a lead-acid battery? |
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Definition
| # of hours a battery can supply a given current flow |
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Term
| what units is batterys capacity expressed |
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Definition
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Term
| what electrolyte is used in lead acid battery |
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Definition
| mixture of sulfuric acid and water |
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Term
| does specific gravity of the electrolyte in a lead-acid battery increase or decrease as the battery becomes discharged. |
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Definition
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Term
| what is the specific gravity of a fully charged lead acid battery? |
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Definition
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Term
| how many cells in a 24volt lead acid battery |
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Definition
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Term
| range of temperatures of the electrolyte in a lead acid battery that does not require a correction when measuring its specific gravity? |
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Definition
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Term
| what instrument is used to measure the specific gravity of the electrolyte in a lead acid battery? |
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Definition
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Term
| how do you treat a lead-acid battery compartment to protect it from corrosion? |
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Definition
| (tar base) paint of polyurethane enamel |
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Term
| what is used to neutralize spilled electrolyte from a lead-acid battery |
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Definition
| solution of bicarbonate of soda and water |
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Term
| How high should the elctrolyte level be in a properly serviced lead-acid battery? |
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Definition
| only up to the level of the indicator on the cell |
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Term
| what is the open circuit voltage of a lead acid cell? |
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Definition
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Term
| what gases are released when a lead acid battery is being charged? |
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Definition
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Term
| what precautions should be taken in the maintenance shop where both lead-acid and nickel cadmium batteries are serviced? |
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Definition
| 2 types of batterys should be kept seperate and the tools used on one type should not be used on the other. |
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Term
| what electrolyte is used in nickel cadmium battery? |
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Definition
| potassium hydroxide and water |
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Term
| why do you not use a hydrometer to measure the state of charge in nickel-cadmium battery? |
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Definition
| electrolytes do not enter into the chemical changes that occur when the battery is charged or discharged. |
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Term
| is the electrolyte level of a nickel cadmium battery lowest when the battery is fully charged or fully discharged. |
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Definition
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Term
| what is the result of cell imbalance in a nickel cadmium battery? |
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Definition
| low internal resistance allows current to flow between the unbalanced cells and generate heat. |
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Term
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Definition
| large current flow allowed by low internal resistance causes the middle cells to produce more heat than they can dissipate. |
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Term
| how can thermal runaway be prevented? |
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Definition
| monitoring the temperature of the middle cells and controlling the charging current to prevent and excess of current flowing into the battery |
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Term
| how it is possible to know when a nickel-cadmium battery is fully charged? |
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Definition
| completely discharge the battery and give it a constant current charge to 140% of its ampere-hour capacity |
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Term
| what is used to neutralize spilled electrolyte from nickel cadmium battery? |
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Definition
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