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,75 K lt T_(C)(B)lt 100K`
C. `B=10T,75KltT_(C)(B)lt100K`
D. `B=10T,T_(C)(B)=75K`

Answer

B

Explanation

With increase in temperature, `T_(C)` is decreasing `T_(C)(0)=100KT_(C)=75K` at `B=7.5T`
Hence at `B=5T, T_(C)` should lie between 75 K and 100 K. Hence, the correct option should be (B).