# Joule's Law in the E-Book

Discussion in 'Feedback and Suggestions' started by retched, Jan 28, 2010.

1. ### retched Thread Starter AAC Fanatic!

Dec 5, 2009
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States:
Like any semiconductor device, the zener diode is sensitive to temperature. Excessive temperature will destroy a zener diode, and because it both drops voltage and conducts current, it produces its own heat in accordance with Joule's Law (P=IE). Therefore, one

I may be overlooking something but I've known Joule's Law as H = RI$^2$

2. ### jpanhalt AAC Fanatic!

Jan 18, 2008
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E=RI

That's too short, so here are some more words.
John

3. ### retched Thread Starter AAC Fanatic!

Dec 5, 2009
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So the E-Book is wrong and I am wrong?

From Encyclopedia Britannica:

Mar 24, 2008
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5. ### StayatHomeElectronics Well-Known Member

Sep 25, 2008
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Both the ebook and you are correct.

P = I*E -- power (dissipated as heat) equals current multiplied by voltage.
E = I*R -- voltage across an element is current multiplied by resistance.

substitute E back into the power equation

P = I*(I*R)
P = I$^{2}$*R = RI$^{2}$

6. ### retched Thread Starter AAC Fanatic!

Dec 5, 2009
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If it confused someone of my caliber and expertise, It could also confuse a third grader.

It was just a note, but it seemed like a error to me. Seeing a formula I usually equate to Ohms Law with Joules name next to it, threw up a flag. I thought it was a case of the missing exponent.

Thanks for clearing that up.