Message:

<p>[QUOTE=&quot;-jeffB, post: 2788219, member: 27832&quot;]No, he did it exactly right. There are two meter units in the numerator, and meter-squared in the denominator; m times m over m squared is 1.</p><p><br /></p><p>Resistivity is given in <b>ohm-meters</b>, not ohms per meter. Think of it this way: resistance goes <i>up</i> as <i>distance</i> (length) increases, but goes <i>down</i> as <i>cross-sectional area</i> increases. A fatter conductor has less resistance for a given length; a thinner one has more.</p><p><br /></p><p>So, imagine you&#039;ve got a 1mm square cross-section wire with a resistance of one ohm per millimeter. A one-meter length of that wire would have a resistance of one thousand ohms.</p><p><br /></p><p>Stack ten one-meter lengths side-by-side, and the resistance of the bundle would be one hundred ohms -- ten 1Kohm resistances in parallel.</p><p><br /></p><p>Stack one hundred one-meter wires in a ten-by-ten bundle, and the resistance of the bundle would be ten ohms.</p><p><br /></p><p>The resistance of the whole thing goes <i>up</i> with length (meters), but <i>down</i> with cross-section (meters squared). So, to state the resistivity of the material, you measure its resistance (in ohms), <i>divide</i> by its length (in meters), and <i>multiply</i> by its cross-section (in square meters). The resulting unit is ohm-meters. (Not to be confused with the measuring device...)[/QUOTE]</p><p><br /></p>

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in