How to Calculate Ohm's Law
What is Ohm's Law?
Ohm's Law describes the fundamental relationship between voltage, current, and resistance in electrical circuits. It states that the current flowing through a conductor is directly proportional to voltage and inversely proportional to resistance.
Formula
The calculator solves for the missing value using V = I × R
- V
- I × R — I × R
- I
- I value — Variable used in the calculation
- R
- R value — Variable used in the calculation
Step-by-Step Guide
- 1Enter any two of the three values: voltage (V), current (I), or resistance (R)
- 2The calculator solves for the missing value using V = I × R
- 3Results display the calculated value with step-by-step work shown
Worked Examples
Input
V = 12V, R = 4Ω
Result
I = 3A
12 ÷ 4 = 3 amps
Common Mistakes to Avoid
- ✕Confusing milliamps (mA) with amps (A) — 1A equals 1000mA
- ✕Forgetting to convert kilohms (kΩ) to ohms (Ω) before calculations
Frequently Asked Questions
Does Ohm's Law apply to all materials?
No, it applies only to ohmic materials where resistance remains constant. Non-ohmic materials like diodes and thermistors have variable resistance.
What happens with zero resistance?
Zero resistance would create a short circuit with theoretically infinite current, which is why fuses and circuit breakers protect circuits.
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