M

#### Midnight Oil

- Jan 1, 1970

- 0

law. I ran into the formula for finding the total resistance in a parallel

circuit, struggled with it's meaning...and I want to be sure I understand

the formula:

R(tot) = 1

-------------

1 + 1 + 1

-- -- --

R1 R2 R3

I broke the formula down like this:

R(tot) = 1 <--- E (volts)

---------------

1 + 1 + 1

-- -- -- <--- I (amps)

R1 R2 R3

In other words, the addition of 1/R1, 1/R2, and 1/R3 reveals the

current when 1 volt is applied to the circuit (E/R). Then, once we know

the current, we can divide the 1 volt by the current to reveal the total

resistance R= (E/I).

In other words, 1/Rx reveals the amount of current in one branch of the

parallel circuit, and adding these together gives us the total current in

the circuit when 1 volt is applied. If we divide 1 volt by that value, we

get the resistance in the circuit when one volt is applied.

Is my understanding of the equation correct?

I thought it was, until I read further in the book. It explained that

the reason for the 1/Rx was because it is expressing conductivity rather

than resistance.

I thought it was interesting that 2 interpretations of the formula

could co-exist...or was my own interpretation of the formula wrong?

Is it just a coincidence that the amount of conductance is equal to the

amount of current flowing when 1 volt is applied?

Thanks!

- Jamie

The Moon is Waxing Crescent (7% of Full)