Ohm's Law

In direct-current (DC) circuits, Ohm's Law is simple andlinear. Suppose a resistance having a value of R ohms carries a current of I amperes. Then the voltage across the resistor is equal to the product IR. There are two corollaries. If a DC power source providing E volts isplaced across a resistance of R ohms, then the current through theresistance is equal to E/R amperes. Also, in a DC circuit, if E volts appear across a component that carries I amperes, then the resistance of that component is equal to E/I ohms.

Mathematically, Ohm's Law for DC circuits can be stated asthree equations:

E = IR

I = E/R

R = E/I

When making calculations, compatible units must beused. If the units are other than ohms (for resistance), amperes (for current), and volts for voltage), then unit conversions should be made before calculations are done. For example, kilohms should be converted to ohms, and microamperes should be converted to amperes.

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More resources from around the web: - Erik Max Francis's The laws list ("Laws, rules, principles, effects, paradoxes, limits, constants, experiments, & thought-experiments in physics") includes Ohm's Law and is one of our favorite links. - Useful Electronics Links may lead to more information.

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