Conductor and Insulator

Thread Starter

Lightfire

Joined Oct 5, 2010
690
Hello,

Good thing I remember this question.:D

We say that a thing is a conductor if it has a low resistance, and an insulator if it has a high resistance.

So, somebody says that a wood for example has a very high resistance, 20 million ohms or so. but i have a question. for example if a current or electric that has a resistance of 20 millions also, can the wood carry the electric or will the wood melt?

Pls. i need clarification for this.;)

thanks

Catapult
 

#12

Joined Nov 30, 2010
18,159
1) any insulator can be overcome with enough voltage. Just think of a direct lightning strike. Nothing can survive that flowing through it. You can use metal to re-route the current, but in a pass through, nothing can survive.

2) it's all about Watts Law. However much current goes through the wood will heat it a little or heat it a lot. P=Esquared/R
 

Adjuster

Joined Dec 26, 2010
2,148
Most of the substances that make up wood change chemically when they are heated before they can become liquid, so wood generally burns rather than melting.

Typically with a small voltage applied over a given length wood will pass a very little current, the amount very much depending on how dry it is. At higher voltages it is common for the current to increase suddenly as the wood begins to break down electrically and chemically. This breakdown is not very predictable, so wood is not safe for use as an insulator.
 

DerStrom8

Joined Feb 20, 2011
2,390
for example if a current or electric that has a resistance of 20 millions also, can the wood carry the electric or will the wood melt?
Hi catapult!

The flow of electrical current itself does not have resistance. The conductor (or insulator, as the case may be) does. However, as previously mentioned, enough voltage can overcome the resistance. Air is usually considered an insulator, because the resistance is very high (generally greater than 1,000,000,000 ohms). However, as mentioned earlier, lightning is able to travel through air because the voltage is extremely high.
Der Strom
 
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