Enter any two electrical values and instantly calculate the other two. Covers voltage (V), current (I), resistance (R), and power (P) using Ohm's Law and Watt's Law.
Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R): V = I × R. It describes the relationship between voltage, current, and resistance in an electrical circuit.
Voltage is measured in Volts (V), current in Amperes or Amps (A), resistance in Ohms (Ω), and power in Watts (W).
Voltage = Current × Resistance (V = I × R). For example: 2 amps through 50 ohms = 100 volts.
Watt's Law relates power to voltage and current: P = V × I. Combined with Ohm's Law: P = I² × R and P = V² / R. These four formulas form the complete set for circuit analysis.
Using Ohm's Law: R = V / I. If you know the voltage across a component and the current flowing through it, you can calculate resistance mathematically.
Direct Current (DC) flows in one direction — used in batteries, electronics. Alternating Current (AC) reverses direction periodically — used in mains electricity. Ohm's Law applies directly to DC and to AC resistive circuits.
Ohm's Law applies to ohmic (linear) conductors at constant temperature. Non-linear components like diodes, transistors, and LEDs do not follow Ohm's Law exactly. Temperature also affects resistance in most materials.