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