Ohm's Law
Despription of the Ohm's Law definition and resistor calculation
Ohm's law states that the strength of the electrical current flowing through an object is proportional to the applied electrical voltage. If an electrical resistance defined as voltage to current is constant, i.e. independent of voltage and current, then this is referred to as ohmic behavior.
In fact, the assumption of constant resistance only applies to a limited extent and only for some substances; especially for metals at constant temperature. You can find information about the temperature behavior of various materials and an online calculator here.
The Ohm's Law defines one of the most important rules for calculating electrical circuits.
Formulas for Ohm's law
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 \(R\) in Ohm bekannt sind:
\(\displaystyle U=I· R\) \(\displaystyle 1V = 1A· 1Ω\)
Example
Calculation of the resistance of a load at \(230\) volts and a current of \(4.5\) amperes
\(U=230V\)
\(I=4.5A\)
\(\displaystyle R=\frac{U}{I}=\frac{230}{4.5}=51.1Ω\)
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