Ohm's Law Calculator
Solve fundamental electrical circuits using Ohm's Law. Enter any two known values to compute the remaining two variables along with the calculations and formulas.
Ohm's Law Solver
Results
I = V / RHow to Use Ohm's Law
Ohm's Law is the most fundamental principle in electrical engineering. It describes the relationship between voltage, current, and resistance in an electrical circuit.
The Formulas
The primary formula is:
From this base formula, we can solve for any variable:
- Voltage ($V$) is equal to Current ($I$) multiplied by Resistance ($R$):
V = I * R - Current ($I$) is equal to Voltage ($V$) divided by Resistance ($R$):
I = V / R - Resistance ($R$) is equal to Voltage ($V$) divided by Current ($I$):
R = V / I - Power ($P$, Watts) represents the rate of electrical energy transfer:
P = V * IorP = I² * RorP = V² / R
Step-by-Step Worked Example
Problem: A heating element is connected to a 240V power source. An ammeter measures a current flow of 12 Amps. Find the resistance of the heating element and the total power consumed.
- Identify Knowns: Voltage ($V$) = 240 V, Current ($I$) = 12 A.
- Select Formula for Resistance: $R = V / I$.
- Calculate Resistance:
R = 240V / 12A = 20 Ω (Ohms). - Select Formula for Power: $P = V \times I$.
- Calculate Power:
P = 240V * 12A = 2880 W (or 2.88 kW).
Frequently Asked Questions (FAQs)
What are the units of measurement in Ohm's Law?
Voltage is measured in Volts (V), Current is measured in Amperes or Amps (A), Resistance is measured in Ohms (Ω), and Power is measured in Watts (W).
Does Ohm's Law apply to AC circuits?
Yes, but with modifications. For AC circuits, resistance is replaced by impedance (Z), which includes both resistive and reactive elements (capacitance and inductance). The formula becomes V = I × Z.
What is a simple way to remember Ohm's Law?
A common memory aid is the "Ohm's Law Triangle". Place V at the top, and I and R at the bottom. Cover the letter you want to solve for, and the remaining letters show the formula (cover V, see I next to R meaning I × R; cover I, see V over R meaning V / R).