Question

Calculate the limiting value of the magnetic field for which Nb will act as a
superconductor at 4 K. Take Bac(0) as 1970 Oe and Tc for Nb to be 9.25 K.

Answer 1

Answer on Question #51242, Physics, Solid State Physics

Calculate the limiting value of the magnetic field for which Nb will act as a superconductor at $4\mathrm{K}$ . Take $\mathrm{B_{ac}(0)}$ as 1970 Oe and Tc for Nb to be $9.25\mathrm{K}$ .

Solution

Fig.1

According to Meissner effect dependence of the magnetic field on the temperature is given by Eq.(1) (see Fig.1)

$$B (T) = B _ {a c} (0) \left(1 - \frac {T ^ {2}}{T _ {C} ^ {2}}\right)$$

where $T = 4K$ , $T_{C} = 9.25K$ ; $B_{ac}(0) = 1970Oe$

Then

$$B (T = 4) = 1 9 7 0 \left(1 - \frac {4 ^ {2}}{9 . 2 5 ^ {2}}\right) = 1 6 0 1. 6 O e$$

Answer: $B(T = 4) = 1601.6Oe$

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