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'''Basic formulas calculating resistance, current, voltage, and power-'''
'''Basic formulas calculating resistance, current, voltage, and power-'''
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where:
where:
<br>
<br>
*V= voltage (Measured in Volts)
*V= voltage (Measured in [[Wikipedia:Voltage|Volts]])
*I= current (Measured in Amperes)
*I= current (Measured in [[Wikipedia:Electric_current|Amperes]])
*R= resistance (Measured in Ohms)
*R= resistance (Measured in [[Wikipedia:Electrical_resistance|Ohms]])
*P= power (Measured in Watts)
*P= power (Measured in [[Wikipedia:Electric_power|Watts]])
Ohm's Law
Ohm's Law
<math>V=I*R</math>
<math>V=I*R</math>
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*note 2 values must be given to find unknown
*note 2 values must be given to find unknown


To find proof of this 'power law', we need the definition of power, which is: the rate at which work is done (on moving charges)
 
<math>
P\ =  dW \over dt
</math>
But:
<math>
W =
[[Category:Electrical engineering]]
[[Category:Electrical engineering]]
[[Category:Electricity]]

Latest revision as of 08:19, 12 June 2009

Basic formulas calculating resistance, current, voltage, and power-
where:

  • V= voltage (Measured in Volts)
  • I= current (Measured in Amperes)
  • R= resistance (Measured in Ohms)
  • P= power (Measured in Watts)

Ohm's Law <math>V=I*R</math>

The definition of resistance requires us to regard it as a derived quantity. Resistance is associated with particular objects and not materials. For any device, we 'supply' a electric potential difference (voltage) and a current, and take the ratio of these two measured quantities to find resistance, as per 'Ohm's Law'. The elementary case of this law states that the relation is linear for all values of voltage and current, but this is not true. At high temperatures (generally, non-standard conditions) the linearity breaks down, in loose analogy to yield strength of a solid (continuum).


Power Law <math>P=V*I</math>
<math>P=(I^2)*R</math>
<math>P=(V^2)/R</math>

  • note 2 values must be given to find unknown