Power consumption from different mobile devices
In electrical engineering, power consumption often refers to the electrical energy over time supplied to operate an electrical appliance.
The energy used by equipment is always more than the energy really needed. This is because no equipment is 100% efficient. Power is wasted as heat, vibrations and/or electromagnetic radiation.
Power consumption is usually measured in units of kilowatt hours (kWh).
More accurately, power is the rate of consumption of energy, measured in watts or horsepower.
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Electricity Consumption in 2009Source: Enerdata Statistical Energy Review