You are given a number of 8 [tex]\Omega[/tex] resistors, each capable of dissipating only 1.0 W without being destroyed. What is the minimum number of such resistors that you need to combine in series or in parallel to make a 8 [tex]\Omega[/tex] resistance that is capable of dissipating at least 5.6 W?(adsbygoogle = window.adsbygoogle || []).push({});

My approach is probably wrong, and so I need someone to help me find the mistake:

[tex]5.6 \mbox{ W} \leq n \cdot m \cdot 1.0 \mbox{ W}[/tex]

The minimum case is when [tex]n=m[/tex], and so

[tex]5.6 \mbox{ W} \leq n^2 \cdot 1.0 \mbox{ W} \Rightarrow n \geq \sqrt{5.6} \Rightarrow n = 3[/tex]

The minimum number of resistors is then 9.

Any help is highly appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Resistors (easy, but tricky question)

**Physics Forums | Science Articles, Homework Help, Discussion**