1. The problem statement, all variables and given/known data A current flows in a circular loop consisting of a single turn.If the same wire is bent into a circular loop of 2 turns and the same current is passed through the loop,the magnetic flux density at the centre will change by a factor of ...? (ans: 4 ) Relevant equations B = (mu0 * N*I)/2r The attempt at a solution For the 1st loop, B = (mu0 *I)/2r To find B' after bending, the length of the wire remains unchanged = 2*pi*r so to form 2 circular loops the radius has to be halved for each loop? which makes B' = (mu0 * N*I)/(2r/2) B' = (mu0 * 2*I)/(r) ? so change in flux = B-B'/B = 3 Thanks in advance.