INTERESTING QUESTION with unlimited current supply into a dead short any point will rise because of it. some voltage will have to be present because of current hugging that point. it is just like asking somebody to go to las vegas but only half way then stop divide the remaining distance and go half way stop and divide again and go half way and stop and so on. Mathematicly speaking he will never get there allways something to divide.

 

Darn, even the wire won't burn!

 

Darn, even the wire won't burn!

You bet!!

 

But do the electrons (or holes or fields or whatever flavor one likes) actually stop to do the math?

 

But do the electrons (or holes or fields or whatever flavor one likes) actually stop to do the math?

Atomic particles do not take to math kindly unlike engineers!

 

Hi Guys,

The following query would sound a bit ridiculous and abstract but it suddenly popped up in my head.

What would happen if I were to apply a purely sinusoidal AC voltage across a zero resistance conductor (theoretically, a super conductor) ? Zero resistance would mean the conductor is assumed to carry infinite current thru it (at least theoretically).

However, it would be interesting to note the behaviour of the AC current waveform since the current cannot be limited by way of 'frictional resistance' as the lattice structure inside the super conductor is considered to be absent.

Also the super conductor is assumed to possess zero inductance!

Kind Regards,
Shahvir

the current would be limited by the internal resistance of the source.

 

the current would be limited by the internal resistance of the source.

I've considered an ideal source, i.e, zero internal resistance!

 

So... with an ideal supply and an ideal dead short across said supply...

There will be zero Ohms. Across any infinitesimal portion of the circuit there will be zero volts dropped. Across the total circuit there will be ∫of all zeros = zero volts. Zero times zero equals zero.

The ideal source has a voltage of zero.

 

The ideal source has a voltage of zero.

Terminal voltage, yes! Internal EMF is present but does not appear externally for measurement as mentioned earlier. But all this has been said before.

 

This is a typical division by 0 error. It warrants no discussion

Good call. The important question to ask is "why would applying an ac voltage from a perfect voltage source accros zero impedance (which is the important detail) have any useful consequence?"

The answer is: It doesn't.

If you apply AC or DC to zero impedance, you have no power and thus no energy transfer = not useful.

 

Good call. The important question to ask is "why would applying an ac voltage from a perfect voltage source accros zero impedance (which is the important detail) have any useful consequence?"

The answer is: It doesn't.

If you apply AC or DC to zero impedance, you have no power and thus no energy transfer = not useful.

My query is for academic interest and should be taken in that sense as such

 

Hmm..
How about plotting a graph of Infinity*sin(t). At one instant it would be Infinity*1/2 other instant infinity*1 and -Infinity*1/2. The graph would still be sinusoidal but something you can not plot.
Another graph that you can not plot is.
F(x) = 1; for all rational values of x,
F(x) = 0; for all irrational values of x.

 

Hmm..
How about plotting a graph of Infinity*sin(t). At one instant it would be Infinity*1/2 other instant infinity*1 and -Infinity*1/2. The graph would still be sinusoidal but something you can not plot.
Another graph that you can not plot is.
F(x) = 1; for all rational values of x,
F(x) = 0; for all irrational values of x.

Thanx for ur suggestion, but math was something which always annoyed me!

 

Will there be a disturbance on the space-time continuum?

Almost: The fuse blows, or the sinusoidal voltage source goes into current limiting. That is, if they are present. Otherwise someone better find a fire extinguisher!
There's always some practical complication that throws a wrench into our dreams of reality.

 

Almost: The fuse blows, or the sinusoidal voltage source goes into current limiting. That is, if they are present. Otherwise someone better find a fire extinguisher!
There's always some practical complication that throws a wrench into our dreams of reality.

Like I said, no resistance in wire would also ensure no heating effect. The wire won't burn.

 

Almost: The fuse blows, or the sinusoidal voltage source goes into current limiting. That is, if they are present. Otherwise someone better find a fire extinguisher!
There's always some practical complication that throws a wrench into our dreams of reality.

Blowing of fuse is very much a practical concept......not consistent with my hopelessly theoretical idea!

 

Real-world superconductors have both resistance (albeit very tiny) and inductance.

Where did you get this fact? Last I heard, it was a quantum property of zero, an absolute.

There will be inductance, unlike resistance, it is unavoidable, and useful for energy storage in a superconductor. Of course, the flip side is every superconductor we have ever seen shuts down if the magnetic flux gets too high.

I remember a company making superconducting wire. They used (I think) a copper jacket as the insulator. When zero is compared to a finite resistance, the finite resistance is an insulator. During their motor experiments with this wire they connect to it using alligator clips.

Other effects I'm hoping for (they exist at really low temperatures, but not in the "high" temperature realm)...

Thermal Superconductivity
Zero Viscosity (not sure of the real name of this, but helium near absolute exhibits it).

 

100,000 years is not eternety. Ergo R is greater than zero, even if negligably.

 

There are materials that approach superconductivity, but aren't. Tried looking them up on Wikipedia, but couldn't find it, I remember reading about it way back when. They have a designation of their own, Ultra low resistance, or some such. Thing is, superconductors are a quantum phenomena, not to be confused with classic physics. They really are zero ohms internally, and will conduct current in a closed loop eternally. The catch is the magnetic limits, they break down in intense magnetic fields.

Right now they are confusing the heck of physicists, the classic theory (cooper pairs) has broken down with the new high temp materials. Last I checked there are two new theories, to handle different variations of chemistry/structure, each explains a different case. Interesting times, in a good way.

 

current in a closed loop eternally

The jolly old electron buzzing round and round the jolly old nucleus (in free space) conforms to this definition.

So is free space a superconductor?