Calculator · Electrical Engineering
Ohm's Law Calculator
Ohm's law links the voltage across a linear resistor, the current through it and its resistance. Give two of the three; the third and the absorbed power follow.
Inputs
Passive sign convention: each element is oriented from → to, v = V(from) − V(to), current is positive from → to, and p = v·i > 0 means the element absorbs power. Signed voltage and current are allowed; zero is a valid value except where it would leave R undefined.
Results
Current I = V/R
2 A
| Voltage V | 12 V |
|---|---|
| Current I | 2 A |
| Resistance R | 6 Ω |
| Absorbed power p = V·I | 24 W |
Explore in the Lab
Open this resistor in the Electrical Networks Lab
The Lab drives R1 with an ideal source V1 = V; R1 then carries the same current I.
Technical reference
V = I·R
I = V/R, R = V/I
p = V·I = I²R = V²/R
- V
- voltage across the resistor[V]
- I
- current through it, same reference direction[A]
- R
- resistance (> 0)[Ω]
- p
- absorbed power[W]
Valid for linear, time-invariant resistors.
Solving for R needs a non-zero current, and V and I must have the same sign.