Question 1

What is Ohm's Law?

Accepted Answer

Ohm's Law states that voltage equals current times resistance: V = I × R. It describes how current flows through a conductor under a given voltage and resistance.

Question 2

How do I calculate power from voltage and current?

Accepted Answer

Electrical power P = V × I. You can also derive it as P = I² × R or P = V² ÷ R depending on which two values you know.

Question 3

What units does this calculator use?

Accepted Answer

Voltage in volts (V), current in amperes (A), resistance in ohms (Ω), and power in watts (W). For small currents use mA (1 A = 1000 mA).

Question 4

Can I enter decimal and milliamp values?

Accepted Answer

Yes. Enter any decimal value in each field. For a 20 mA LED current, just type 0.02 in the current field in amperes.