Riddle: What Metal Conducts Electricity, But Not Heat?

If you can’t answer the riddle, don’t feel bad. Metal conductors usually conduct electricity and heat. Usually, that’s true, but researchers at the Department of Energy’s Lawrence Berkeley National Laboratory and at the University of California, Berkeley, have found that¬†vanadium dioxide can conduct electricity without conducting heat.

The Wiedemann-Franz Law states that good conductors of electricity are also good conductors of heat. Vanadium dioxide not only switches from an insulator to a conductor at 67C (152F), but it appears that it also doesn’t conduct as much heat as that law predicts while it is in its electrically conductive phase.

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The Soda Locker Vending Machine

With the rising popularity of electronic textbooks and laptops being used for schoolwork, the ubiquitous high school locker is becoming less and less necessary. So, students are left with a private storage space that they don’t really need. Why let it go to waste¬†when you’re an enterprising young man with budding electronics and fabrication skills?

[Mistablik] is one such high school student who decided to take advantage of his unused locker. After a “wouldn’t it be cool if…” discussion with his friends, [Mistablik] decided to use his summer break to construct a soda vending machine that fit entirely within his school locker. Quite an ambitious project for a high school student, but the result speaks for itself.

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