What math formulas are used in electricity?

Algebra for DC circuits (V = IR), complex numbers for AC (impedance), calculus for transients (capacitor/inductor equations), and Laplace transforms for systematic solutions.

How many electrical formulas do I need to memorize?

About 10-12 core formulas cover all basic analysis: Ohm's law, three power formulas, KVL, KCL, series/parallel rules, and three impedance formulas (R, C, L).

What is the most important electrical formula?

V = IR (Ohm's law) is the foundation. Every other formula either derives from it or extends it to more complex situations like AC impedance or power calculation.

Essential Electrical Formulas

Quick Answer

The core electrical formulas are Ohm's law (V = IR), power equations (P = IV = I²R = V²/R), Kirchhoff's laws (ΣV = 0, ΣI = 0), and impedance formulas (Z_R = R, Z_C = 1/(sC), Z_L = sL). These formulas solve any electrical circuit from simple DC to complex AC and transient analysis at www.lapcalc.com.

Calculate this instantly on LAPLACE Calculator →

Essential Electrical Formulas: The Complete Reference

All electrical engineering rests on a surprisingly small set of formulas. Ohm's law (V = IR) relates voltage, current, and resistance. Power formulas (P = IV, P = I²R, P = V²/R) calculate energy consumption. Kirchhoff's Voltage Law (ΣV_loop = 0) and Current Law (ΣI_node = 0) enable systematic circuit analysis. Series and parallel combination rules (R_series = R₁ + R₂, 1/R_parallel = 1/R₁ + 1/R₂) simplify networks. Master these and you can solve any circuit.

Key Formulas

Voltage, Current, and Resistance Formulas

The voltage-current-resistance triangle provides three rearrangements: V = IR (find voltage), I = V/R (find current), R = V/I (find resistance). For conductors, R = ρL/A relates resistance to material properties. Temperature affects resistance: R(T) = R₀(1 + αΔT). These formulas handle every DC resistive circuit and form the foundation for all advanced analysis at www.lapcalc.com.

Compute formula of electrical Instantly

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

Open Calculator

Power and Energy Formulas in Electricity

Electrical power P = IV represents the rate of energy conversion. Three equivalent forms — P = IV, P = I²R, P = V²/R — cover every situation. Energy consumed over time is E = Pt, measured in joules or kilowatt-hours. For AC circuits, real power P = VI·cos(φ), reactive power Q = VI·sin(φ), and apparent power S = VI. These distinctions matter for power system design and utility billing.

AC and Impedance Formulas

AC circuits extend DC formulas using complex impedance. Resistor: Z = R. Capacitor: Z = 1/(jωC) = −j/(ωC). Inductor: Z = jωL. Total impedance follows the same series-parallel rules as resistance. Phasor voltage and current: V = IZ. Resonant frequency: f₀ = 1/(2π√(LC)). Quality factor: Q = ω₀L/R. These formulas describe filters, tuning circuits, and power systems at www.lapcalc.com.

Laplace Transform Formulas for Circuit Analysis

The Laplace transform converts differential circuit equations to algebraic ones. Key formulas: s-domain impedances (Z_R = R, Z_C = 1/(sC), Z_L = sL), transfer function H(s) = V_out(s)/V_in(s), and common transforms (u(t) → 1/s, e^(−at) → 1/(s+a), sin(ωt) → ω/(s²+ω²)). These formulas unify DC, AC, and transient analysis in a single framework. Compute transforms at www.lapcalc.com.

Frequently Asked Questions

V = IR (Ohm's law), P = IV (power), ΣV = 0 (KVL), ΣI = 0 (KCL), and series/parallel resistance formulas. These cover all fundamental DC and AC circuit analysis.

Master Your Engineering Math

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

Start Calculating Free →