Wednesday, 28 May 2014
There are a couple of different ways to measure electricity, but the main one is the watt-hour.
The watt (W) is a measure of electrical power. Light bulbs are marked with a watt rating, such as 40 W, and so are appliances such as air-blow heaters (around 1,000 W). This gives an indication of the amount of electrical power they need to work.
Electricity consumption is a combination of the amount of electricity (that is, the watt) and the period of time for which it’s used. So a standard measure of electricity consumption is the amount of watts used over an hour: the watt-hour (Wh). For example, a 40 W light bulb turned on for one hour will use 40 Wh of electricity.
An electricity bill records the number of kilowatt-hours (kWh) consumed over a period, which is usually around three months. A kilowatt-hour is simply a thousand watt-hours.
1. Measuring total electricity consumption in kWh
Power(W) x Number of hours
1000
kWh = measurement unit for electricity usage (kilowatt per hour)
kw = 1000watt
h = hour
2. Measuring cost of electricity consumed
Cost = Electricity used (kWh) x Rate of electricity tariff
For easier calculation method, visit the tenaga nasional website.
An electricity bill records the number of kilowatt-hours (kWh) consumed over a period, which is usually around three months. A kilowatt-hour is simply a thousand watt-hours.
Power(W) x Number of hours
1000
kWh = measurement unit for electricity usage (kilowatt per hour)
kw = 1000watt
h = hour
Cost = Electricity used (kWh) x Rate of electricity tariff
For easier calculation method, visit the tenaga nasional website.
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.
Electric power, is the rate of doing work, measured in watts, and represented by the letter P. The term wattage is used colloquially to mean "electric power in watts." The electric power in watts produced by an electric current I consisting of a charge of Q coulombs every t seconds passing through an electric potential (voltage) difference of V is
- P = work done per unit time QV/t = IV
where
- Q is electric charge in coulombs
- t is time in seconds
- I is electric current in amperes
- V is electric potential or voltage in volts
Electricity generation is often done with electric generators, but can also be supplied by chemical sources such as electric batteries or by other means from a wide variety of sources of energy. Electric power is generally supplied to businesses and homes by the electric power industry. Electricity is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using electricity meters, which keep a running total of the electric energy delivered to a customer.
Electricity is a very convenient way to transfer energy, and it has been adapted to a huge, and growing, number of uses. The invention of a practical incandescent light bulb in the 1870s led to lighting becoming one of the first publicly available applications of electrical power. Although electrification brought with it its own dangers, replacing the naked flames of gas lighting greatly reduced fire hazards within homes and factories. Public utilities were set up in many cities targeting the burgeoning market for electrical lighting.
The Joule heating effect employed in the light bulb also sees more direct use in electric heating. While this is versatile and controllable, it can be seen as wasteful, since most electrical generation has already required the production of heat at a power station. A number of countries, such as Denmark, have issued legislation restricting or banning the use of electric heating in new buildings. Electricity is however a highly practical energy source for refrigeration, with air conditioning representing a growing sector for electricity demand, the effects of which electricity utilities are increasingly obliged to accommodate.
Electricity is used within telecommunications, and indeed the electrical telegraph, demonstrated commercially in 1837 by Cooke and Wheatstone, was one of its earliest applications. With the construction of first intercontinental, and then transatlantic, telegraph systems in the 1860s, electricity had enabled communications in minutes across the globe. Optical fibre and satellite communication technology have taken a share of the market for communications systems, but electricity can be expected to remain an essential part of the process.
The effects of electromagnetism are most visibly employed in the electric motor, which provides a clean and efficient means of motive power. A stationary motor such as a winch is easily provided with a supply of power, but a motor that moves with its application, such as an electric vehicle, is obliged to either carry along a power source such as a battery, or to collect current from a sliding contact such as a pantograph.
Electronic devices make use of the transistor, perhaps one of the most important inventions of the twentieth century, and a fundamental building block of all modern circuitry. A modern integrated circuit may contain several billion miniaturised transistors in a region only a few centimetres square.
Electricity is also used to fuel public transportation, including electric buses and trains
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