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The Power of Electricity
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Terms in this set (9)
What is electrical power?
Power is rate of change in energy.The symbol for power is P. The units for measuring power are joules per second. A joule (J) is the unit for measuring energy.
What is electrical power?
One joule per second is also called one watt (W). Electrical power is the rate of change of electrical energy. In other words, electrical power is the amount of electrical energy that is changed into other forms of energy each second.
How is electrical power calculated?
You can calculate electrical power if you know the voltage and current in a circuit: Power (in watts) = current (in amperes, symbol I) x voltage (in volts, symbol V) or P = IV
How is electrical power calculated?
By rearranging the terms in this equation, you can find the current or the voltage of the circuit, too. Current = power over voltage or I = P over V
Voltage = power over current or V = P over I
What is a power rating?
You have likely seen a light bulb with a power in watts marked on it, such as 40 W, 60 W. You may have noticed a similar power in watts on devices such as hair dryers, kettles, or MP3 players.
What is a power rating?
These power ratings tell you how many joules of energy the device uses each second operation. (Recall that 1 W is J/s.)
How is amount of electrical energy calculated?
You can use a power rating to calculate the amount of electrical energy that a device uses. The mathematical equation that defines power is: Power ( in watts) = energy (in joules) over time (in seconds) or P = E over I
or Energy (in joules, J) = power ( in watts, W) x time ( in seconds, s) or E = Pt
What is a kilowatt-hour?
A Joule is a small amount of energy. You use about one joule of energy to lift a medium-sized apple a distance of one metre. Energy devices use fairly large amounts of energy, so a larger unit of energy is used to describe them.
What is a kilowatt-hour?
A Kilowatt-hour (kWH) is the same amount of energy as 1000 W used over a period of 1 h
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