Memorize two formulas and you have them all. No Ohm’s law chart is necessary.

E = I x R, is one expression of Ohm’s law meaning: **E**lectromotive force (Volts) equals the **I** ntensity of electrons (Amps), multiplied by the **R** esistance of current flow (Ohms).

Other Ohm’s law formulas include: I = E/R and R = E/I.

In addition P = I x E. **P** ower equals current times voltage.

Other Ohm’s law formulas include: I = P/E and E = P/I.

Even if you memorize all of these formulas to avoid having to keep a chart with you, inconsistent use of these formulas can cause you to forget them in time. An easier way is to memorize two formulas and use basic algebra to recall the others.

**Memorize E = I x R**. Why memorize this particular Ohm’s law formula? The formula has the letters listed alphabetically. E, I, and R.

To recall the formula for I from E = I x R, use algebra. What is done to one side of an equation must be done to the other to keep both sides of the equation equal.

Take E = I x R and divide both sides of the equation by R to determine the value of I. E/R = I x R/R. Therefore E/R = I.

**Memorize P = I x E**. Why memorize this particular Ohm’s law formula? If you can remember how to spell pie, it is done.

To recall the formula for I from P = I x E, use algebra.

P/E = I x E/E. Therefore P/E = I.

So if two values or more are known, P,I,E, and R, can all be determined using algebra.