# Unknown Resistance

1. May 10, 2012

### xenocid3r

Hello

I will be taking Circuits next semester. I am trying to work around a circuits book by myself.
Now I hope this is the right section to post it (its not homework, just a concept I have problem understanding).

I know that to check resistance in series I need to add the resistor value. and in parallel the total resistance will be the reciprocal of each resistor.

Is it possible to measure a circuit without any given resistor values.

If I am measuring the resistance of two or more resistors in series (or in parallel) what will be the best method to get approximation or exact values for whole of the resistors?

2. May 10, 2012

### Floid

When you measure a circuit what you are measuring is the total impedance of the circuit.

So if you measured two resistors in series what you would read would be the sum of those two resistances. You would then have to work backwards (using some additional information) if you wanted to find out the value of each individual resistor.

3. May 10, 2012

### xenocid3r

ok I got it.

So if I have lets say 4 or 5 resistors, can be more. The resistance of each 2 resistors will be the sum of both of them.

So lets assume I measure 2 of the resistors,then I get x sum ofthese 2 resistors. lets say 2 resistorsfrom this network of resistors is the sum of 500 ohms.
I know that for series I check all of the resistors, create equations for each pair and solve for them.

But how would I measure if the resistors are in parallel. I know that the parallel resistance for 2 resistors is R1R2/(R1+R2). How would I measure the resistance of more then 2 resistors?

Thanks for the help Floid