Ohm law calculator
Ohm law calculator
Current, voltage, resistance: calculations related to Ohm law. Enter known values (e.g. voltage and resistance of conductor) and we'll show you step-by-step how to transform basic formula and find out missing value (e.g. current)

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Calculations data - enter values, that you know here

Current (I)
Voltage (U)
Resistance (R)

Units normalization

Voltage (U)Show source230 [V]230\ \left[V\right]
Resistance (R)Show source460 [Ω]460\ \left[\Omega\right]
Current (I)

Result: Current (I)

Used formulaShow sourceI:=UR I:=\frac{ U}{ R}
ResultShow source12\frac{1}{2}
Numerical resultShow source0.5 [A]0.5\ \left[A\right]
Result step by step
1Show source(230)(460)\frac{\left(230\right)}{\left(460\right)}Removed unneded parenthesis
2Show source230460\frac{230}{460}Simplified fractions
3Show source12\frac{1}{2}Result
Numerical result step by step
1Show source0.50.5Result
Units normalizationShow source0.5 [A]0.5\ \left[A\right]

Some facts

  • The Ohm's law states that the electric current is directly proportional to the voltage (i.e. the difference of potentials between the ends of the conductor) and inversely proportional to resistance of the conductor.
  • Mathematically, Ohm's law can be written in the following form:
    I=URI = \frac{U}{R}
  • For practical reasons, all conductors (and also any electric or electronic elements that may appear in the circuit) are divided into:
    • linear elements - meeting Ohm's law (in given circumstances), which can be called "ohmic",
    • non-linear elements - where Ohm's law doesn't apply (like diodes)
  • It's important to note, that Ohm's law is stated as "for a conductor in given state", meaning that other cirumstances are intentionally ignored.
    For example, the temperature change:
    • if the voltage is increased, then the current will increase (by Ohm's law),
    • this may potentially increase the temperature of the conductor,
    • the resistivity of materials usually changes with temperature, so:
      • if the material is a metal (like copper), then the resistance will increase and so will reduce the current,
      • for some other materials (like germanium), the resistance will decrease and so will further increase the current,
    • in summary: the voltage increase changed indirectly also the resistance - additional factor to consider. It doesn't break the Ohm's law, but introduces additional factor (resistance change when temperature changes).

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