# Faraday's law superconducting [duplicate]

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When we say flux can't be changed through superconducting coil , because resistance is zero , So this implies there is no induced emf in the coil , If it is so what makes current flow in the coil when we change magnetic field through the coil ? How much current is induced in superconducting coil when flux is changed That is what I wanted to know

## marked as duplicate by safesphere, John Rennie, stafusa, Kyle Kanos, ZeroTheHeroAug 29 '18 at 13:53

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## 1 Answer

When we change magnetic field through a superconducting coil, the emf will be produced as per Faraday's induction law.

In response, the current in the coil will be changing and its magnetic field will be trying to cancel the external magnetic field and, therefore, the induced emf.

Although the coil does not have any resistance, the current in it won't be changing instantaneously, since the coil has some inductance. Therefore, as long as the external magnetic field keeps changing, the emf in the coil won't be zero ($emf=L\frac {di}{dt})$.

If, at some point, the external magnetic field stops changing, the induced emf will go to zero, but the current, flowing in the coil at that time, will continue without changing and without any emf.

• @AbhishekBajpai Glad to help. – V.F. Aug 31 '18 at 11:28