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Old Oct 29th 2010, 09:09 AM   #1
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Zero Resistance

Hi PHF
Reference Ohms law. V=IR,
A simple question but unclear.


Is there a material which would have constant resistance? the temperature would not change when the current is flowing through it. Thanx
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Old Oct 29th 2010, 10:11 PM   #2
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As temperature increases due to dissipation of heat in the wires, the resistance will usually increase for some metal wires. Unless the wires have no resistance, otherwise it is quite impossible for no change in resistance in wires.
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Old Dec 28th 2010, 08:36 PM   #3
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Originally Posted by anwaar View Post
Hi PHF
Reference Ohms law. V=IR,
A simple question but unclear.


Is there a material which would have constant resistance? the temperature would not change when the current is flowing through it. Thanx
There is no material having a constant resistance at all temperatures. The resistance of most metals increase with increase in temperature and those of semi-conductors decrease with increase in temperature.
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Old Feb 8th 2011, 09:08 PM   #4
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0 resistance is impossible. electricity through a nedium is always resisted.
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Old Feb 8th 2011, 09:31 PM   #5
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Originally Posted by woodjutt View Post
0 resistance is impossible. electricity through a nedium is always resisted.
yes, you are right! If zero resistance existed, infinite current also have been existed. Although many materials can have very low values (Eg.Superconductors), no material can offer zero resistance!
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Old Feb 9th 2011, 01:34 PM   #6
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Originally Posted by davis_devasia View Post
yes, you are right! If zero resistance existed, infinite current also have been existed. Although many materials can have very low values (Eg.Superconductors), no material can offer zero resistance!
Well.....

The electric current in a superconductor is carried by Cooper pairs of electrons. The Cooper pairs form what is known as a "Bose-Einstein condensate" which has no resistance to flow. Ignoring impurities what causes a small, but measurable, resistance in most superconductors is that the bulk of the material is not uniformly in the superconducting phase. i.e. there are domains where the material is superconducting and domains where it is not. I see no theoretical reason why we couldn't make an entire sample superconducting if we wanted to put the effort into it.

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