simple demonstration of superconducting and non superconducting state. It is possible to destroy the superconductivity of a superconductor by application of intense magnetic field. If a super conductor is placed in a sufficiently strong magnetic field the super conductor becomes a normal conductor i.e. it regains its resistance. The value of magnic field at which superconductivity is destroyed is called the threshold or critical magnetic field. It is denoted by Subscript[H, c] and is found to be a function of temperature. If we plot a graph of critical magnic field versus temperature, the curve is approximately parabolic. It is given by the relation Subscript[H, c] = Subscript[H, o][1 - (T/Subscript[T, c])^2] where Subscript[H, o] is the critical magnetic field at 0 K.

According to this relation, at O K Subscript[H, c] = Subscript[H, o] & at T = Subscript[T, c] , Subscript[H, c] = 0 The curve defines the boundary below which superconductivity is present and outside it, the superconductivity behaves as a normal conductor. From the above, we conclude that the superconductor state is stable only in some definite ranges of magnetic field and temperatures.

• This is an interactive demonstration. It will ask you to enter the values yourself and you can see the result.
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