Voltage, Current, and Resistance
The state of an ideal resistor is completely specified by the voltage
across it (call it volts) and the current passing through
it (
amperes, or simply ``amps''). The ratio of voltage to
current gives the value of the resistor (
resistance in
Ohms). The fundamental relation between voltage and current in a
resistor is called
Ohm's Law:
![$\displaystyle V(t) = R \cdot I(t)$](http://www.dsprelated.com/josimages_new/mdft/img1961.png)
The electrical power in watts dissipated by a resistor R is given by
![$\displaystyle {\cal P}= V\cdot I = \frac{V^2}{R} = R\cdot I^2
$](http://www.dsprelated.com/josimages_new/mdft/img1962.png)
![$ V$](http://www.dsprelated.com/josimages_new/mdft/img1959.png)
![$ I$](http://www.dsprelated.com/josimages_new/mdft/img1861.png)
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