js5895 said:

Hi,

I'm studying electrical, what's the best way to remember the P.I.R.E.

wheel.

Here's a non-algebra method of deriving the 12 equations of the P.I.R.E

wheel from just 2 "triangle" diagrams. So, if you can remember the two

triangle diagrams, you can quickly come up with the whole wheel.

First, there's the P = IE triangle:

P

------

I | E

By covering up either P, I, or E with your finger, what remains will remind

you of the formula for what you covered up:

P (covered) = I * E

I (covered) = P / E

E (covered) = P / I

For the remaining 9 formulas of the wheel, start with the E = IR triangle:

E

-----

I | R

By covering up either E, I, or R with your finger, what remains will remind

you of the formula for what you covered up:

E (covered) = I * R

I (covered) = E / R

R (covered) = E / I

Now take the same E = IR triangle, and multiply both the top and left side

by I. You now get:

E * I

-----------

I * I | R

Because P = E * I (from the first triangle), and I * I = I^2 (that is, I

squared), you can rewrite this as:

P

---------

I^2 | R

By covering up either P, I^2, or R with your finger, what remains will

remind you of the formula for what you covered up:

P (covered ) = I^2 * R

I^2 (covered) = P / R, so I = square root of (P / R)

R (covered) = P / I^2

Now go back to the E = IR triangle, but this time multiply both the top and

left side by E. This time you get:

E*E

---------

E*I | R

This is the same as:

E^2

----------

P | R

By covering up either E^2, P, or R with your finger, what remains will

remind you of the formula for what you covered up:

E^2 (covered) = P * R, so E = square root of (P * R)

P (covered) = E^2 / R

R (covered) = E^2 / P

You've now developed all 12 equations of the P.I.R.E. wheel.

--- Wayne