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Ohm’s Law Calculator

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What is Ohm’s law & How do I use it?

Sometimes when we’re working on a circuit we need to calculate voltage, current, resistance or power. We’re all familiar, or at least should be, with ohm’s law, outlined below. But if you want to just double-check, then this ohm’s law calculator is a great place to start.

So, I is our current, V is our voltage and R is our resistance.

  • To Calculate Voltage;
    • We can use resistance (R)  multiplied by current (I) – R x I
    • Power (P) divided by current (I) – P / I
    • Or the square root of power (P) multiplied by resistance – √ P x R
  • For Current;
    • We can use the square root of power (P) divided by resistance (R) – √ P / R
    • Power (P) divided by voltage (V) – P / V
    • Voltage (V) divided by resistance (R) – V / R
  • Resistance is calculated by;
    • Voltage (V) divided by Current (I) – V / I
    • Voltage (V) squared divided by power – V2 / P
    • Power (P) divided by current squared – P / I2
  • Finally, To Calculate Power;
    • Voltage (V) multiplied by current (I) – V x I
    • Resistance(R) multiplied by current(I) squared – R x I2
    • Voltage (V) squared divided by resistance (R) – V2 / R

But if you want to make sure you’ve got it right, it can be easier to use an ohm’s law calculator just like this one!

Simply enter two values into the fields above to find the remaining two.

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For a more in-depth overview of Ohm’s Law, as well as practical examples of how it’s used, check out this post over at Gray Code!