Question

the circular loops of equal radii are placed coaxially at some separation the first is cut and a battery is inserted in between to drive a current in it the current changes slightly between the variation in resistance with temperature during this period loops attract each other tell why and how?

Answer 1

     As the DC current flows in the first loop, the temperature of the conducting wire increases due to heat dissipated by the wire in the circuit.  So its resistance increases slightly and steadily at a slow rate.  Then the DC current decreases slowly and slightly at a small rate.

   The magnetic flux passing through the second loop is product of its area and magnetic field due to the magnetic field caused by the current in the first loop.  This magnetic flux decreases as the current decreases steadily.

   So a current (small) is induced in the second loop that opposes this change.  So current in the second loop flows in the same direction (clockwise or anticlockwise) as in the first loop.  Their magnetic moments are in the same direction. So they attract.

   The situation is like the two parallel loops are similar to two parallel wires with current in the same direction, they attract each other.