Electronics - Ohms Law

Show/Hide:DefinitionsFormulae Instructions


This page allows you to input two out of the four values for a steady-state 'Ohm's Law' problem, and calculate the remaining values, regardless of which two values are provided.
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Voltage v
The unit of electromotive force or electric pressure, the potential difference between two points in an electrical circuit, measured in Volts.
Current I
The rate of flow of electricity through a conductor, measured in Amperes.
Resistance R
In dc circuits, the opposition a material offers to current, measured in Ohms (Ω) In ac circuits, resistance is the real component of impedance, and may be higher than the value measured at dc.This page only contains formulae for steady-state (DC) circuits.
Power P
The rate of work done, measured in Watts (= joules/second)
Direct Current. Compare with Alternating Current (AC)


Diagram of the "Magic Triangle" formulae


  1. Fill in at least two boxes with the values that you know
  2. Change the units for all 'input' fields, if required
  3. Change the units for any output fields necessary
  4. Click the 'CalcResult' button below the input fields
  5. The value of the blank fields will be calculated
  6. A 'Results Area' will be displayed below.
  7. All known values will be shown. (Values for which insufficient information was given will also be identified.)
  8. To do further calculations simply change any values in the input fields and click the 'CalcResult' button again. (Press the 'Clear Form' button if you want to empty all of the input fields.)
  9. Press the 'Clear Results' button if you wish to discard the first results, otherwise further calculations will be added into the same area.
  10. Click the 'CalcResult' button again
  11. Click the 'Print Results' button to display all current results in a new, printable window.
D.C. Values


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