# Homework Help: Reisitor Problem

1. Mar 1, 2005

### Berg

You are given a number of 10 ohm resistors, each capable of dissopating only 1 w without being destroyed. What is the minimum number of such resistors that you need to combine in series or parrallel to make a 10 ohm resistance that is capable of dissipating at least 5w? Hmm i know the answer is 3 series of 3 in parrallel but i dont know how to work to achieve this answer.

Also when doing circuit problems do u find the current at each resistor? or each branch?

2. Mar 1, 2005

### dextercioby

Each branch from a circuit has a current (or intensity,the old name).So that should be very clear.As for your problem,it's not that simple.U must take into acount that
[tex[ P=RI^{2} [/tex] and a bunch of inequalities forthe various powers dissipated in resistors.Plus u'll need to know the formulas giving the equivalent resistance for a seris arrangement & for a parallel one,respectively.U should (hopefully) be able to write down a system of inequalities which MUST BE SOLVED INTO $$\mathbb{N}$$.

Good luck!

Daniel.