| ENERGY AND POWER UNITS CONVERSION DEFINITIONS, ONLINE CALCULATORS, EQUATIONS |
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| Energy in general is defined as the capacity for doing work. Power (P) is the rate of doing work or the rate of using energy: P=Work/t=Energy/t, where t is time. Although casually the terms energy and power are often used interchangeably we see technically they have different meanings.
The SI unit of energy or work is the joule (J). In general, work done by a constant force F when it moves an object by distance L in direction of force is Work=F*L. A joule is the work done by a force of one newton for a distance of one metre. The SI derived unit of power is watt (W). Watt is power required to produce or use of one joule of energy per second. In electric field with voltage V over distance L force acting on change Q is equal to F=V/L*Q (particularly, in the field of 1 volt/meter, force of 1 newton is acting on one coulomb charge). Substituting this into the general expression of power gives the equation for power required to move charge Q in uniform electric field: P=F*L/t=V*Q/t. The rate of charge flow Q/t is called electric current I. Replacing Q/t with I in the above expression yields familiar formula for instanteneous value of electric power: P=V*I. For more detailed analysis of electric energy and power terms, see Electric power primer. |
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| POWER UNIT CONVERSION CALCULATOR | ENERGY UNIT CONVERSION CALCULATOR | |||||||||||||||||
| Note: IT- International Table th- thermochemical unit |
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| © 2007 L.Rozenblat | ||||||||||||||||||