Ohm's Law and resistor calculation

Despription of the Ohm's Law definition and resistor calculation

Ohm's Law

The Ohm's Law defines one of the most important rules for calculating electrical circuits.

In its original form, it determines the resistance in ohms from a current and voltage measurement when \(U\) in volts and \(I\) in amps are known

\(\displaystyle R=\frac{U}{I}\)           \(\displaystyle 1Ω=\frac{1V}{1A}\)

Calculation of current \(I\), if \(U\) in volts and \(R\) in ohms are known

\(\displaystyle I=\frac{U}{R}\)           \(\displaystyle 1A=\frac{1V}{1Ω}\)

Calculation of the voltage \(U\), if \(I\) in amperes and \(R\) n ohms are known

\(\displaystyle U=I· R\)           \(\displaystyle 1V = 1A· 1Ω\)


Calculation of the resistance of a load at \(230\) volts a current of \(4.5\) amperes


\(\displaystyle R=\frac{U}{I}=\frac{230}{4.5}=51.1Ω\)