Ohm's Law

Related wiki pages : Electronic Theory, Voltage, Current, Impedance, Resistors

What is it?
Ohm's Law is named after Georg Ohm, a German physicist who postulated it in 1827. His treatise described measurements of voltage and current in simple circuits, using various lengths of wire as resistors. The following diagram shows a voltage source V passing through a resistor R creating a current I



The following diagram shows a current source I through a resistor R, causing a potential drip (voltage V)



Ohm's Law states that the current that passes between two points on a conductor is directly proportional to the potential difference (voltage) between the points and inversely proportional to the to the resistance of the conductor between the points.

so, $$I = \frac{V}{R}$$

where
 * "I" is the current in amperes,
 * "V" is the potential difference between the ends of the resistor in volts, and
 * "R" is the resistance of the resistor, measured in ohms

Ohms Law can also be used in impedance (resistance to AC) calculations thus:

$$I = \frac{V}{Z}$$

where
 * "I" is the current in amperes,
 * "V" is the potential difference between the ends of the resistor in volts, and
 * "Z" is the Impedance (AC resistance) of the resistor, measured in ohms