# Find current from voltage drop?

Discussion in 'Electronic Basics' started by js5895, Mar 23, 2005.

1. ### js5895Guest

Hi,

The voltage drop formula:

K x I x L x 2
E = ----------------
CMA

I know all the values, except "I", so is there a formula to find "I".

Thanks.

2. ### GarethGuest

Are you saying that you know all the values in your equation except I,
and you want to find I? If so that is simple algebra.

Multiply both sides of the equation by CMA:-

E x CMA = K x I x L x 2

Then divide both sides by K x L x 2:-

E x CMA
---------- = I
K x L x 2

--

3. ### Kitchen ManGuest

See Gareth's answer, unless you don't know either E or I, in which case
you cannot find the answer from the known information.

I have a question. What are K, C, M and A? I'm assuming this is a
formula for the drop across an inductor, where E = I * XL, and XL =
2*Pi*f*L, so somehow Pi*f = K/(CMA)? Thanks.

4. ### John LarkinGuest

Probably wire loss E in volts.

L = length
I = current
CMA = wire cross-sectional area, circular mils
K = fudge factor
2 = round trip

John

5. ### js5895Guest

Thank You very much.
If thats simple algebra, I don't know algebra, lol.

K = Approximate/Exact K of wire
I = Current
L = Length of wire, one way
2 = There and back
E = Voltage drop
CMA = Circular Mill Area of wire  