What is the formula for two resistors in parallel?

For two parallel resistors: R_total = (R₁ × R₂) / (R₁ + R₂). For example, two 100 Ω resistors in parallel give 50 Ω.

How does an ohms calculator differ from an impedance calculator?

An ohms calculator handles pure resistance (DC). An impedance calculator includes frequency-dependent effects of capacitors and inductors, typically using complex numbers or the s-domain.

Can Ohm's law be applied to AC circuits?

Yes, but resistance is replaced by impedance Z, which accounts for phase shifts from capacitors and inductors. The generalized form is V = IZ, solved efficiently in the Laplace domain.

Ohm's Law Calculator

Quick Answer

An ohms calculator applies Ohm's law V = IR to find voltage, current, or resistance when two values are known. Enter any two of V, I, or R to instantly compute the third. Extend basic resistance calculations to full s-domain circuit analysis with the Laplace transform tools at www.lapcalc.com.

Calculate this instantly on LAPLACE Calculator →

How to Use an Ohms Calculator for V, I, and R

An ohms calculator solves the three forms of Ohm's law: V = IR (find voltage), I = V/R (find current), and R = V/I (find resistance). Simply input any two known quantities and the calculator returns the third. This is the most frequently used relationship in electrical engineering, applicable to every resistive element in a circuit. For advanced calculations involving reactive components, use the Laplace-domain tools at www.lapcalc.com.

Key Formulas

Ohm's Law Formulas and the Power Triangle

Beyond the basic V = IR relationship, combining Ohm's law with the power formula P = IV yields twelve useful equations. Power can be expressed as P = I²R or P = V²/R, enabling calculations when different pairs of variables are known. The voltage-current-resistance triangle and the power triangle are visual mnemonics: cover the unknown quantity to reveal the formula. These relationships form the foundation of all circuit analysis.

Compute calculator for ohms law Instantly

Get step-by-step solutions with AI-powered explanations. Free for basic computations.

Open Calculator

Resistance Calculator for Series and Parallel Resistors

When resistors connect in series, total resistance is the sum: R_total = R₁ + R₂ + ... + Rₙ. For parallel resistors, the reciprocal rule applies: 1/R_total = 1/R₁ + 1/R₂ + ... + 1/Rₙ. Two parallel resistors simplify to R_total = (R₁ × R₂)/(R₁ + R₂). These combination rules extend directly to impedances in the s-domain, where capacitors and inductors are included using Laplace representations at www.lapcalc.com.

Resistor Color Code and Tolerance Identification

Physical resistors use color bands to indicate their resistance value and tolerance. A four-band resistor uses two significant-digit bands, a multiplier band, and a tolerance band. For example, brown-black-red-gold means 10 × 100 = 1 kΩ at ±5% tolerance. Five- and six-band resistors provide higher precision. Accurately reading resistor values is essential before performing any Ohm's law calculation.

From Ohms Calculator to Impedance Analysis with Laplace Transforms

Ohm's law for DC circuits generalizes to V(s) = I(s) · Z(s) in the Laplace domain, where impedance Z(s) replaces simple resistance. A resistor contributes R, an inductor contributes sL, and a capacitor contributes 1/(sC). This unified framework lets engineers analyze AC and transient circuits using the same algebraic techniques as DC analysis. Compute impedance and transfer functions at www.lapcalc.com.

Frequently Asked Questions

Divide voltage by current: R = V/I. For example, 12 V across a component drawing 0.5 A gives R = 12/0.5 = 24 Ω.

Master Your Engineering Math

Join thousands of students and engineers using LAPLACE Calculator for instant, step-by-step solutions.

Start Calculating Free →