You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter rjmockster
- Start date

- Status
- Not open for further replies.

- Location
- Indianapolis

Don't forget that you can substitute from E=IR to P=IE and vice-versa. An example would be to substitute for E, P=I(IR) becomes P=I^2R.

I find that an Ohm's law equation can always be solved by remembering one rule:

I x R = E can be changed to

E / R = I or

E / I = R

It might be clearer to use numbers:

2 X 3 = 6 can be changed to

6 / 3 = 2 or

6 / 2 = 3

Given any two variables the third can always be deduced. I also think of this as being able to "unmultiply" something by dividing it in the opposite direction.

100w / 120v = .833333A and you need resistance

that's E / I = R or 120v / .833333A = 144ohms

[ May 09, 2003, 03:54 PM: Message edited by: physis ]

- Location
- Massachusetts

Watts = volts x amperes, P = E x I. however, this is only where you have a purely resistive load or unity power factor, no inductive loads. Where inductive loads are supplied, watts = volts x amperes x power factor, P = E x I x PF.

- Location
- Florida

Re: Basic theory/formula's

DOCTOR WATTS pocket guide is pretty good too by Mark Shapiro.

DOCTOR WATTS pocket guide is pretty good too by Mark Shapiro.

- Status
- Not open for further replies.