## 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*:

(Ohm's Law)

where we have indicated also that the voltage and current may vary
with time (while the resistor value normally does not).
The electrical *power*in

*watts*dissipated by a resistor R is given by

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