Calculadora de la Ley de Ohm
Calcula voltaje, corriente, resistencia y potencia
Required Parameters
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Quick Answer
Ohm's Law: V = I × R. Enter any two values to solve voltage, current, resistance, or power (P = V × I) for DC resistive circuits.
Ohms Calculator
Use this free ohms calculator to solve Ohm's law instantly: enter any two of voltage (V), current (I), and resistance (R) — the tool computes the third plus power (P) when relevant.
Quick start: Pick what you want to find (Voltage, Current, Resistance, or Power), enter the other two values, and read the result.
Ohms calculator formulas
| Find | Formula |
|---|---|
| Voltage | V = I × R |
| Current | I = V / R |
| Resistance | R = V / I |
| Power | P = V × I = I²R = V²/R |
The Ohm's law triangle
Cover the value you want:
- V covered → multiply I × R
- I covered → divide V ÷ R
- R covered → divide V ÷ I
Worked example
12 V supply, 470 Ω resistor:
- I = 12 / 470 = 25.5 mA
- P = 12 × 0.0255 = 0.31 W → use a 1/2 W resistor minimum
Unit tips
- mA → A: divide by 1,000 (250 mA = 0.25 A)
- kΩ → Ω: multiply by 1,000 (4.7 kΩ = 4700 Ω)
- Engineering shorthand: 4k7 = 4700 Ω, 10u = 10 µA
When Ohm's law does not apply
- LEDs and diodes — non-linear Vf, not constant R → LED resistor calculator
- AC with L or C — use impedance Z, not R → Reactance calculator
Related tools
- Ohm's Law Calculator — same engine, Ohm's law focused entry
- Voltage divider
- Parallel resistor calculator
- Electrical power calculator
Design Notes
Ohm's Law applies precisely to Ohmic materials where resistance remains constant regardless of current or voltage. In practical engineering, resistors heat up when dissipating power (P = I²R), which can alter their resistance (Temperature Coefficient of Resistance). Always verify that your calculated power dissipation is below the resistor's actual wattage rating (typically leave a 50% margin).
Common Mistakes
- 1
Mixing up units: Forgetting to convert milli-amps (mA) to Amps (A) before calculating.
- 2
Ignoring power dissipation: A 1/4W resistor will burn up if your calculation yields 0.5W, even if the resistance is correct.
- 3
Applying it to non-linear components: Ohm's law does not directly apply to diodes, LEDs, or transistors which have dynamic resistance.
Engineering Handbox
1. Identify knowns: V = 12, R = 470 2. Use Formula: I = V / R 3. Calculate: I = 12 / 470 = 0.02553 A (25.53 mA) 4. Calculate Power: P = 12 × 0.02553 = 0.306 W
Knowledge Base
¿Cuáles son las 3 fórmulas principales de la Ley de Ohm?
V = I × R (Voltaje), I = V / R (Corriente) y R = V / I (Resistencia). Son reordenamientos algebraicos de la relación descubierta por Georg Ohm en 1827.
¿Cómo uso el triángulo de Ohm?
Coloque V arriba, I abajo a la izquierda y R abajo a la derecha. Tape la variable que busca: V tapada → I × R. I tapada → V ÷ R. R tapada → V ÷ I.
¿Puedo usar la Ley de Ohm para corriente alterna (AC)?
Solo para cargas puramente resistivas. Para circuitos con capacitores o inductores, reemplace R con impedancia (Z), donde Z = √(R² + X²).
¿Cómo calculo la potencia con la Ley de Ohm?
P = V × I, P = I² × R o P = V² / R. Elija la fórmula según las dos variables conocidas.
¿Por qué la Ley de Ohm no funciona para LEDs?
Los LEDs son dispositivos no lineales con voltaje directo fijo. Su resistencia cambia con la corriente. Use nuestra calculadora de resistencia para LEDs.
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