Ohm's Law Calculator
Calculate Voltage, Current, Resistance, and Power.
Ohm's Law: The Foundation of Electronics
If you want to understand how electricity works, you must understand Ohm's Law. Discovered by Georg Ohm in 1827, it describes the relationship between Voltage, Current, and Resistance.
The Water Pipe Analogy
The easiest way to visualize electricity is to think of water flowing through a pipe:
- Voltage (V) = Water Pressure. It is the force pushing the electrons. Measured in Volts.
- Current (I) = Flow Rate. It is how much water (electrons) is actually moving. Measured in Amps.
- Resistance (R) = Pipe Size. A narrow pipe resists flow; a wide pipe allows it. Measured in Ohms (Ω).
The Formulas
The primary formula is V = I × R. From this, we can derive:
I = V / R(Current = Voltage divided by Resistance)R = V / I(Resistance = Voltage divided by Current)
What about Power (Watts)?
Power (P) describes the rate of energy consumption. The formula is P = V × I.
Example: A 100-Watt lightbulb running on 120 Volts draws about 0.83 Amps.
Practical Usage
Why does this matter?
Circuit Safety: If you try to push too much Current through a wire with high Resistance, the energy is converted to Heat. This is why overloaded extension cords melt and start fires. Engineers use Ohm's Law to determine the correct fuse size (Amps) to protect your home.