What happens to current and voltage in a superconductor with zero resistance?

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Discussion Overview

The discussion revolves around the behavior of current and voltage in superconductors, particularly in the context of Ohm's law (V=IR) when resistance approaches zero. Participants explore the implications of zero resistance on current and voltage, addressing misconceptions and limitations in real-world applications.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that if resistance (R) is zero, then according to Ohm's law, current (I) would become infinite, questioning the validity of this interpretation.
  • Others argue that if R=0, there would be no potential difference (V), suggesting that this leads to a short circuit rather than infinite current.
  • One participant points out that as resistance decreases, current increases, but emphasizes that there are limits in real systems that prevent infinite current.
  • Another participant elaborates on these limits, mentioning that even with all generating stations combined, there is a maximum current capacity that cannot be exceeded.
  • Some participants introduce the relationship between power (P), current (I), and voltage (V), noting that as resistance approaches zero, power also tends to decrease if voltage is held constant.
  • A participant mentions that superconductors can carry a finite current with zero voltage difference, questioning the perceived mystery of this phenomenon and clarifying that practical values of voltage and current are constrained in real life.

Areas of Agreement / Disagreement

Participants express differing views on the implications of zero resistance in superconductors, with some asserting that infinite current is possible while others counter that practical limitations prevent this scenario. The discussion remains unresolved regarding the interpretation of Ohm's law in the context of superconductors.

Contextual Notes

Participants highlight limitations related to real voltage sources and the internal resistance of batteries and generators, indicating that theoretical models may not fully capture practical realities.

Sagar Singh
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Hi there!
as wee all know V=IR
v= potential difference
I=current
R=resistance
so => I=V/R
and somehow we make Resistance almost equal to 0
then I=V/0
will I become infinity?
or what?

what will happen?
Please clear every situation to me?
 
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Sagar Singh said:
Hi there!
as wee all know V=IR
v= potential difference
I=current
R=resistance
so => I=V/R
and somehow we make Resistance almost equal to 0
then I=V/0
will I become infinity?
or what?

what will happen?
Please clear every situation to me?

You can't do this. If R=0, then you will not have any potential difference, I.e, you have a short! Current doesn't go to "infinity".

Zz.
 
ZapperZ said:
You can't do this. If R=0, then you will not have any potential difference, I.e, you have a short! Current doesn't go to "infinity".

Zz.
Why there will be no potential difference> what is the relation between potential difference and resistance?
 
As resistance gets smaller, current gets larger, yes. But there are limits for real systems.
 
russ_watters said:
As resistance gets smaller, current gets larger, yes. But there are limits for real systems.
LIMITS?? can you please elaborate
 
Sagar Singh said:
LIMITS?? can you please elaborate
Well, let's say you take the output of ALL of the generating stations on Earth. That's going to give you a lot of current capacity. Let's call it 14 zillion amps. OK, now I make R even smaller. Where are you going to get any more current capacity? You can't, so your concept of the equation fails. That's a limit on a real system (and not REALLY a real system, since there are other complications in trying to tie together all the generators on Earth).
 
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Sagar Singh said:
LIMITS?? can you please elaborate
There is also P=IV. Combining that with your expression gives P=V^2/R. So as R goes to 0 so does the power if V is fixed. So the limit is that no real voltage source will actually be able to deliver a constant voltage at arbitrarily low resistance.
 
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DaleSpam said:
There is also P=IV. Combining that with your expression gives P=V^2/R. So as R goes to 0 so does the power if V is fixed. So the limit is that no real voltage source will actually be able to deliver a constant voltage at arbitrarily low resistance.
Power goes toward infiniy, but yes: for real sources, internal limitations get in the way (for batteries: internal resistance, for generators: prime mover power capacity).
 
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We have superconductors thst have zero resistance. We can put a finite current through a superconductor and the voltage difference from one end to the other will be zero. Where is the mystery in that?

We get this question frequently, where people thing that we can set V and I and R to any aribtrary value, and what then? In real life, we can only achieve reasonable value of V and I. R can be measured as the ratio of V to I. No mystery, no infinities.
 
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