Ohm'S Law Calculator
Computes voltage, current, resistance, or power from any two known electrical values
Electrical potential difference in volts
Electrical current in amperes
Electrical resistance in ohms
Enter any two values to calculate the rest
Enter any two values to calculate the rest
Enter any two values to calculate the rest
Enter any two values to calculate the rest
Frequently Asked Questions
What is Ohm's law?
Ohm's law states that voltage equals current times resistance (V = I x R). It describes the relationship between electrical pressure (voltage), flow (current in amps), and opposition to flow (resistance in ohms). It is fundamental to all electrical circuit design.
How do I calculate watts from volts and amps?
Power in watts equals voltage times current: P = V x I. For a 120-volt circuit drawing 10 amps, the power is 1,200 watts. You can also calculate watts from current and resistance (P = I squared x R) or voltage and resistance (P = V squared / R).
What is the relationship between voltage, current, and resistance?
Increasing voltage while keeping resistance constant increases current proportionally. Increasing resistance while keeping voltage constant decreases current. These three quantities are always linked by V = I x R.
When would I use Ohm's law in practice?
Electricians use it to size wires, select fuses, and troubleshoot circuits. If you know a device draws 5 amps on a 120V circuit, you can calculate its resistance (24 ohms) and power consumption (600 watts) to choose the right breaker and wire gauge.
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