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Flashcards in Basic Electricity Deck (77)
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What is meant by inductance?

The ability to store electrical energy in electromagnetic fields.


What is the basic unit of inductance?

The henry.


What does inductive and capacitive reactance cause?

Opposition to current flow in AC circuits.


What constitutes a capacitor?

Two conductors separated by an insulator.


What is the purpose of a capacitor?

It stores electrical energy in electrostatic fields.


What is the basic unit of capacitance?

The farad.


Why should electrolytic capacitors not be used in an AC circuit?

They are polarized. An electrolytic capacitor will pass current of one polarity, but will block current of the opposite polarity.


Why should Nickel Cadmium and Lead Acid batteries not be stored together?

They are chemically opposite and can neutralize each other.


What three things must all electrical circuits contain?

A source of electrical energy, a load to use the energy, and conductors to join the source and the load.


What is Ohm's Law?

E = I x R


Name the elements of Ohm's Law.

Voltage, current, and resistance (volts, amps, and ohms).


What is the basic unit of electrical power in a DC circuit?

The watt.


What are three types of DC circuits, with regard to the placement of various circuit components?

Series, parallel, and series parallel (complex).


What happens in a DC circuit if the voltage is increased but the resistance remains the same?

The current increases.


What could be the problem if a Nickel Cadmium battery fails to deliver?

A cell imbalance or bad cells.


What are the advantages of Alternating Current?

It can be transmitted more readily over long distances, and can be stepped up or down by use of transformers.


What are some things a multi-meter can be used to check?

Amps, volts, ohms.


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.


How many cells are there in a 24-volt lead-acid battery?

12 cells (2v each).


What is the specific gravity of the electrolyte in a fully charged lead-acid battery?

Between 1.275 - 1.300.


What are the effects temperature has on the specific gravity of the electrolyte in a lead-acid battery?

The electrolyte is less dense at higher temperatures and more dense at lower temperatures.


Why is no specific gravity check done on Nickel Cadmium batteries?

There is no real change of the specific gravity of the electrolyte during charge or discharge of a Nickel Cadmium battery.


How can you find the polarity of an electromagnet?

Hold the electromagnet in your left hand with your fingers encircling the coil in the direction the electrons flow. Your thumb will point to the north end of the electromagnet.


In what units is impedance measured?

In ohms.


What is meant by a kilowatt?

1,000 watts.


What is the range of temperatures of the electrolyte in a lead-acid battery that does not require that you apply a correction when measuring its specific gravity?

Between 70 degrees and 90 degrees Fahrenheit.


What instrument is used to measure the specific gravity of the electrolyte in a lead-acid battery?

A hydrometer.


How do you treat a lead-acid battery compartment to protect it from corrosion?

Paint it with an asphaltic (tar base) paint or with polyurethane enamel.


What is used to neutralize spilled electrolyte from a lead-acid battery?

A solution of bicarbonate of soda and water.


How high should the electrolyte be in a properly serviced lead-acid battery?

Only up to the level of the indicator in the cell.