Question

If the key in the arrangement as shown below is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are

A. Concentric circles 

B. elliptical in shape 

C. Straight lines parallel to each other 

D. Concentric circles near the point O but of elliptical shapes as we go away from it

Answer 1

Since the key is taken out due to which there is no magnetic field due to wire. Hence only magnetic field of earth is present and the magnetic field lines of the earth are straight lines parallel to each other.