Resistance and resisitors question

[Silver04STi]

ok I need a total resistance of 1 ohm and 25 watts power handling. At the moment I have access to 1 ohm 10 watt resistors. Here's my plan I am going to run two sets of 1 ohm/10watt resistors in series and then run those two sets in parallel. Essentially I am doubling my resistance then halving it. My question is, how is my power handling multiplied? Since I am using 4 10 watt'ers, am I going to have an effective power handling of 40 watts? I know running them in parallel will half the resistance and double the power handling. I also know that running them in series will double the resistance but I am unsure of the effect on the power handling in series.

[BradC]

Originally Posted by Silver04STi

ok I need a total resistance of 1 ohm and 25 watts power handling. At the moment I have access to 1 ohm 10 watt resistors. Here's my plan I am going to run two sets of 1 ohm/10watt resistors in series and then run those two sets in parallel. Essentially I am doubling my resistance then halving it. My question is, how is my power handling multiplied? Since I am using 4 10 watt'ers, am I going to have an effective power handling of 40 watts? I know running them in parallel will half the resistance and double the power handling. I also know that running them in series will double the resistance but I am unsure of the effect on the power handling in series.

Its been a bit, but IIRC...

When you have resistors in parallel, but they all see the same potential voltage. The current they see will be equal to the Voltage/Resistance.

If you need 1 ohm of resistance with 25W of power, that would be an applied voltage of 5V. P = (e^2)/r or 25=(e^2)/1. Solve for e and you have 5 volts.

So if you have a leg of 2 ohm resistance (two one ohm resistors in series), that would have 5 volts applied across it. With the above equation, P would equal (5^2)/2, for each leg of the circuit. Solve for P and you have 12.5 watts.

If you are using 10w resistors, you will most likely let the smoke out of them. I would not trust that circuit.

[88TSI_Rob]

Originally Posted by Silver04STi

ok I need a total resistance of 1 ohm and 25 watts power handling. At the moment I have access to 1 ohm 10 watt resistors. Here's my plan I am going to run two sets of 1 ohm/10watt resistors in series and then run those two sets in parallel. Essentially I am doubling my resistance then halving it. My question is, how is my power handling multiplied? Since I am using 4 10 watt'ers, am I going to have an effective power handling of 40 watts? I know running them in parallel will half the resistance and double the power handling. I also know that running them in series will double the resistance but I am unsure of the effect on the power handling in series.

Yes, the total would be 40watts. You simply add up the power rating of all the resistors whether or not it's in series or parallel.