when the temperature rises from below the critical temperature point- nothing happens to the current's magnitude until the temperature reaches the critical point. At T->T(0+) the resistance of the super conductor suddenly becomes a finite positive quantity from zero. that's like a step impulse...
Let us suppose that there is a superconducting toroid. Let us also suppose that there is a finite electric current flowing in it. We imagine the temperature of the toroid to be below the critical temperature. Now if we try to raise the temperature of the toroid then due to the law of...