The Foundation of Circuit Analysis
Ohm's law — V = I × R — is the first equation every electrical engineer learns, and it remains the most frequently used throughout their career. Published by Georg Simon Ohm in 1827, it was initially met with skepticism, even costing Ohm his teaching position. Today it is recognized as one of the most fundamental laws in physics, describing how voltage drives current through resistance in any electrical circuit.
Understanding the Triangle
The famous Ohm's law triangle (V on top, I and R on the bottom) provides three rearrangements: V = I×R to find voltage, I = V/R to find current, and R = V/I to find resistance. This simulator lets you fix any two quantities and compute the third. In real circuit design, you typically know the supply voltage and desired current, then calculate the needed resistance.
Series and Parallel Circuits
Real circuits combine resistors in series (end-to-end, sharing current) and parallel (side-by-side, sharing voltage). Series resistors add directly, while parallel resistors combine reciprocally. Two 100Ω resistors in series give 200Ω; in parallel, they give 50Ω. This simulator lets you toggle between configurations and immediately see how total resistance, current, and power change.
Power and Heat
Every resistor converts electrical energy to heat at a rate given by P = I²R. This is why resistors have power ratings — exceed the rating and the resistor overheats and fails. The power equation also explains why high-voltage transmission lines are more efficient: for a given power P = V×I, higher voltage means lower current and thus lower I²R losses in the wires. This simple physics drives the entire electrical grid architecture.