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.

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# Resistors (easy, but tricky question)

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