1.  IF THE MAGNETIC FEILD OUTSIDE A COPPER BOX IS SUDDENLY CHANGED WHAT HAPPENS TO THE MAGNETIC FEILD INSIDE THE BOX ?SUCH LOW RESISTIVITY METALS ARE USED TO FORM ENCLOUSRES WHICH SHIELD OBJECTS INSIDE THEM AGAINST FIELDS.

2.

TWO CIRCULAR LOOPS  OF EQUAL RADII ARE PLACED COAXIALLY AT SOME SEPARATION.THE  FIRST IS

INSERTED IN BETWEEN TO DRIVE A CURRENT IN IT.THE CURRENT CHANGES SLIGHTLY BECAUSE OF THE VARIATIONIN RESITANCE WITH TEMPRETURE.DURING THIS PERIOD THE TWO LOOPS

a ATTRACT EACH OTHER

b REPEL EACH OTHER

c DO NOT EXERT ANY FORCE ON EACH OTHER.

dATTRACT OR REPEL  EACH OTHER DEPENDING ON THE SENSE OF  THE CURRENT.

SIR PLEASE ANSWER BOTH THESE QUESTIONS.