Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value of zero as their temperature is lowered below a critical temperature `T_(C) (0)`. An interesting property of super conductors is that their critical temperature becomes smaller than `T_(C) (0)` if they are placed in a magnetic field, i.e., the critical temperature `T_(C) (B)` is a function of the magnetic field strength B. The dependence of `T_(C) (B)` on B is shown in the figure.
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A superconductor has `T_(C) (0) = 100 K`. When a magnetic field of 7.5 Tesla is applied , its `T_(C)` decreases to 75 K. For this material one can difinitely say that when

Options

A. `B=5T,T_(C)(B)=80K`
B. `B=5T,75KltT_(c)(B)lt100K`
C. `B=10T,75KltT_(c)lt100K`
D. `B=10T,T_(c)=70K`

Answer

B

Explanation

At zero magnetic field `T_(c) (0)=100K`
At `B=7.5T,Tc=75K`

We have drawn a rough diagram of Tc(B) vs B, on which we marked the given points.
For `B=5T,75KltTc(B)lt100K`
`B=10T,Tc(B) lt 75K` exact values we can't find