Derivations of Formulas
So what is a derivation? Well, when selecting a formula to find a missing
value in an electrical problem, the unknown value needs to be by itself on one
side of the equation and the known values need to be on the other side of the
equation. Finding a formula in this format might not be easy. So here's what can
Say you have the formula E = I R well, you in this problem have no access to
all the Ohms Watts formulas. So you need to find R because you have I and E. To
get R by itself, you are allowed by the rules of algebra to do what ever you
want to both sides of the equation to keep it balanced.
So you can divide both sides of the equation by I. That will yield R = E / I.
You then can go ahead and solve for R with the values you know of I and E. Of
course if you have the formulas on a sheet of paper in front of you, none of
this is necessary. You can just look up a formula you need from the list.
So keep in mind that if you ever do need to derive a formula, start with a
formula you have. Then you can:
add the same amount to each side.
subtract the same amount from each side.
multiply each side by the same number.
divide each side by the same number.
square each side.
take the square root of each side.