Ohm's Law

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001

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03

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Toptronic College

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Ohm's Law

Authored by

Jacques Botte for toptronic college www.toptronic.com www.toptroniccollege.org

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A complete circuit must have an unbroken path so I (current) can flow out of the battery V (Voltage Source), through the resistor R (Load) connected to it, and back into the battery. If a connection is removed at any point, the circuit is broken, or Open (Open Circuit).

The relationship between the values of I, V and R is known as Ohm's Law:

The current (I) flowing in a circuit is directly proportional to the applied voltage (V) and inversely proportional to the resistance (R) it is going through.

Current

I gives the value of the current when the voltage and resistance are known.

I quantity is expressed in amperes (A)

$I(amperes)={\dfrac {\text{V (volts)}}{\text{R (ohms)}}}$

Voltage

V gives the value of the voltage when the current and the resistance are known.

V quantity is expressed in volts (V)

$V(volts)=I(amperes)\cdot R(ohms)$

Note In many cases V is represented by ε = EMF (ElectroMagnetic Force) or V is represented by U (volts).

Resistance

R gives the value of the resistance when the current and the voltage are known.

R quantity is expressed in ohms (Ω)

$R(ohms)={\dfrac {\text{V (volts)}}{\text{I (amperes)}}}$

Conductance is the inverse of the resistance.

$G={\dfrac {\text{1}}{\text{R}}}$ in Siemens.