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Resistance equation

Just wondering how you would rearrange the restistance equation 1/R=1/R1+1/R2. I thought I did it correctly but every website does something different so just wanted to check. Thankyou

Reply 1

Joinedup

well I like R=1/((1/R1)+(1/R2)...)

cos it keys nice and easily on my very oldschool calculator without textbook entry.

e.g. for 470 ohm in parallel with 620 ohm

[4][7][0] [1/x] [+] [6][2][0] [1/x] [=] [1/x]

267.3

Reply 2

MissMathsxo

Original post by Joinedup

Thankyou. That's what I got too but didn't know if I had to simplify it

Reply 3

Fysiika07

To simplify it, make the denominator the same by multiplying them:
1/R = [ R2 / (R1R2) ] + [ R1 / (R1R2) ]
= (R2 + R1) / R1R2
Then, flip both sides of the equation:
R = R1R2 / (R1+R2)

Hope this help :smile: