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30 Cards in this Set
- Front
- Back
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ONE KILOWATT is equal to how many watts?
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1,000 WATTS
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What law describes the most fundamental or basic relationships in an electrical circuit?
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OHMS LAW
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What are the 3 elements of Ohms Law?
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VOLTAGE, CURRENT, RESISTANCE
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How would you write Ohms law as an equation?
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E= IxR, R= E÷I, I= E÷R
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If the resistance in a DC circuit remains the same but the voltage doubles what happens to the amount of current flowing in the circuit
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It ALSO DOUBLES
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In DC circuits what unit measures power
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WATTs
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What three elements are required to form a electrical circuit
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SOURCE of electrical energy, LOAD/resistance to use the electricity, & WIRES/CONDUCTORS to connect the source to the load
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DC circuits can take one of three forms or types. What are they
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SERIES, PARALLEL, or SERIES-PARALLEL
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A 24–volt lead–acid battery has how many cells?
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12
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A fully charged lead acid battery has a specific gravity that varies between what two values
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1.275 & 1.300
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You must apply a correction to the specific gravity reading of the electrolyte of a lead acid battery when the temperature is outside of what two values
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Below 70°F or more than 90°F
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What is the reason for having a separate facility for storing and servicing nickel cadmium and lead acid batteries
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The electrolyte in the 2 types of batteries is chemically opposite and the fumes from 1 type can contaminate the electrolyte of the other type
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The state of charge of a nickel cadmium battery cannot be determined by measuring the specific gravity of the electrolyte for what reason?
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There is NO significant change in the specific gravity of the electrolyte as the battery is charged and discharged.
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What is the principal advantage of AC current over DC current
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Power can be transmitted over long distances more efficiently and with smaller wires because the voltage can be easily increase or decreased by a transformer.
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What are the three causes of opposition to current flow in an AC circuit?
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1. RESISTANCE
2. INDUCTIVE REACTANCE 3. CAPACITIVE REACTANCE |
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Define inductance
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an induced voltage which is opposite in direction to the applied voltage
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What component creates capacitance in AC circuits
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Capactiors
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How does a capacitor store electricity
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The energy is stored as a electrostatic charge/field that exists between 2 conductors that are seperated by an insulator.
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What property of an AC circuit is defined by the term Impedance
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TOTAL OPPOSITION to current flow
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What are two reasons that might cause a nickel cadmium battery to fail to deliver its rated capacity
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FAULTY CELLS or CELL IMBALANCE
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What electrical values are measured by a typical multimeter
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Voltage, current, & resistance
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What are the sources of electrical power
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1. mechanical (generator)
2. Chemical ( battery) 3. Photo electric (light) 4. Thermal ( heat ) |
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What is the function of a capacitor
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To store electricity
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What instrument is used to determine the specific gravity of electrolyte in a lead acid battery
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A hydrometer
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What is electromagnetic induction
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The transfer of electrical energy by means of a magnetic field. This is the principle of transformer operation
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How are battery compartments protected against corrosion
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They are coated with special corrosion resistant paints such as bituminous paint.
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What should be the correct electrolyte level in a properly service battery
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It should be approximately 3/8 inches above the plates. If the battery has baffle plates above the cell plates, the electrolyte level should be up to the hole in the baffle plate in each cell.
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What 4 things affect the resistance of an electrical conductor
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1. Material
2. Cross sectional area 3. Length 4. Temperature |
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What are resonant frequencies
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The frequency of alternating current that produces the same inductive reactance and capacitive reactance in a circuit
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What is thermal runway
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A condition that can occur in Ni-Cad batteries in which the battery Overheats because of excess current
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