Ley de Ohm
Aplica la ley de Ohm V = IR. Despeja tensión, corriente o resistencia con conversiones de mA y kΩ y pasos claros.
Fórmula principal
V = IR
How do you use Ohm's law (V = IR)?
Ohm's law is V = I × R. If you know two values, solve for the third: I = V / R or R = V / I. Keep volts, amperes, and ohms consistent (convert milliamps and kilo-ohms first).
Sobre esta herramienta
La ley de Ohm relaciona tensión (voltaje), corriente y resistencia con V = IR. Despeja V, I o R con conversiones claras de mA y kΩ y pasos visibles para circuitos introductorios.
Cómo usar esta calculadora
- Elige la variable que quieres despejar y confirma qué valores ya conoces.
- Introduce los datos en unidades coherentes antes de calcular.
- Comprueba si el resultado es físicamente razonable comparándolo con las entradas.
- Usa el desglose paso a paso para ver cómo se aplicó la fórmula.
Ejemplos resueltos
Example 1: I from 12 V and 4 Ω (IR formula)
I = V / R = 12 / 4.0 = 3.0 A. Sanity check: lower R would draw more current from the same 12 V source.
Example 2: R from 9 V and 30 mA
Convert current first: 30 mA = 0.030 A. Then R = V / I = 9 / 0.030 = 300 Ω. Skipping the mA→A conversion and using 9 / 30 gives 0.3 Ω — wrong by a factor of 1000.
Example 3: V from 0.025 A and 1.2 kΩ
R = 1.2 kΩ = 1200 Ω. V = I R = (0.025)(1200) = 30 V.
Preguntas frecuentes
What is the Ohm's law formula (V = IR)?
V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. Rearrangements are I = V / R and R = V / I. Searches for “ir formula” or “v = ir” mean this same relationship.
How do you use Ohm's law step by step?
Convert to V, A, and Ω, write the form that isolates the unknown, substitute, then multiply or divide. Check that USB-scale currents are often tens to hundreds of mA.
How do I convert mA and kΩ for Ohm's law?
1 mA = 0.001 A and 1 kΩ = 1000 Ω. Convert to amperes and ohms before dividing or multiplying, unless every quantity stays in a consistent milli/kilo set that you track carefully.
Does Ohm's law work for every component?
It models ohmic resistors well under the conditions stated in the problem. Diodes, transistors, and many real devices are non-linear, so V/I is not a single fixed R for all voltages.
How is Ohm's law related to electric power?
Power often uses P = V I, and with Ohm's law you can also write P = I² R or P = V² / R. Use the electric power calculator when the unknown is power rather than V, I, or R alone.