A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be
2:1
1:4
4:1
1:2
Let
be length of wire.
Ist case :
............(1)
2nd Case
using (1) (where n=2)