Units of Electricity Flashcards
The Volt (V) is a unit for measuring
both electric potential difference and electromotive force. The voltage supplied by most automobile storage batteries is 12 volts.
Five common units used in working with electricity and electric circuits are
volt, ampere watt, ohm hertz.
The Ampere (A) is
a unit for measuring electric current—the flow of electric charges. Houses are typically wired to provide a total of 60 or more amperes.
One coulomb is
The amount of electric charge transferred by a current of one ampere in one second.
The Watt (W) is
Electric power—that is, the rate at which electric energy is used to perform work.
Lightbulbs and appliances are usually marked with their wattage, indicating
the rate at which they consume energy.
The normal 120-volt, 15-ampere household circuit can safely handle electrical devices drawing a total of
1,800 watts (1.8 kilowatts).
The mechanical power an electric motor can provide is usually given in
watts or horsepower. (One horsepower equals 746 watts.)
Consumption of electricity is measured in terms of
the kilowatt-hour—the work done by 1,000 watts in one hour.
The relationship of voltage (in volts) to current (in amperes) and resistance (in ohms) is expressed by
Ohm’s Law:
Voltage = (current • resistance)
The Hertz (Hz) is
a measure of the rate at which an alternating current reverses direction.
Each two consecutive reversals in an alternating current are called
a cycle.
Commercially generated alternating current in the United States has a frequency of
60 hertz (cycles per second).
