Ohm's Law defines the relationship between voltage (V), current (I), power (P) and resistance (R) in electrical circuits. It was discovered in 1827 by Georg Ohm (1789 – 1854), a German mathematician and physicist who, as a high school teacher, decided to study Alessandro Volta's new invention: the electromechanical cell (the precursor of the battery).
The relationships between the four important parameters of circuits are as follows:
  1. Voltage (V, in volts) calculations:
  2. Current (I, in amps) calculations:
  3. Power (P, in watts) calculations:
  4. Resistance (R, in Ω) calculations:
To use this calculator, enter a value for any two of the following: voltage, current, resistance, and power.
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