# Electrical Equations Transpoition: solve Zs = Ze+((R1*C1)+(r2*c2)*L)/1000 for L, r2

#### LostValleyBoy

##### New member
Hi all.
I could really help with transposition.

So......
This is how its written in the book

Zs = Ze+((R1*C1)+(r2*c2)*L)/1000

How do I transpose to Find

i) L
ii)r2

I have had a go and got the below but neither work when punched into a calculator

L= (1000*(Zs-Ze))/((R1*C1)+(r2*c2)

r2 = [(1000*(Zs-Ze)-(R1*C1)]/(c2*L)

#### stapel

##### Super Moderator
Staff member
Zs = Ze+((R1*C1)+(r2*c2)*L)/1000

How do I transpose to Find

i) L
ii)r2

I have had a go and got the below but neither work when punched into a calculator

L= (1000*(Zs-Ze))/((R1*C1)+(r2*c2)

r2 = [(1000*(Zs-Ze)-(R1*C1)]/(c2*L)
Please reply showing your work in getting the above answers. Thank you! #### LostValleyBoy

##### New member
Yes I agree its bad bracketing but I don't understand how to transpose.

#### stapel

##### Super Moderator
Staff member
Yes I agree its bad bracketing but I don't understand how to transpose.
Has your class not yet covered how to solve literal equations? Then (besides the fact that this exercise should not have been assigned) what sorts of equations have you been taught how to solve?

Thank you! #### LostValleyBoy

##### New member
Has your class not yet covered how to solve literal equations? Then (besides the fact that this exercise should not have been assigned) what sorts of equations have you been taught how to solve?

Thank you! Hi
I'm not taking a class. Im a 32 year old Electrican. The Zs equation is for earth fault loop impeadence

Zs = Earth(Ground in US) Loop Impeadence
Ze = External Earth Loop Impeadence
R1 = Resistance of Line conductor
C1 = Correction factor for R1
R2 = Resistance of Earth/Ground conductor
C2 = Correction factor for R2
L = Length of circuit

The transposition is to help me with circuit design and determining cable sizes

I thought Maths people would be better to help rather than pompous electrical engineers