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
. An interesting property of superconductors is that their critical temperature becomes smaller than
if they are placed in a magnetic field, i.e., the critical temperature
is functional of the magnetic field strength B. the dependence of
(B) on B is shown in the figure.
A superconductor has
. when a magnetic field of 7.5 tesla is applied, its
decreases to 75 K. for this material one can definitely say that when