A coil   of n  turns and radius   R  carries  a current  I it is  unwound  and
Channel: Doubtnut
Date: 2020-05-24

A coil   of n  turns and radius   R  carries  a current  I it is  unwound  and  rewound to make  a new coil  of radius `(R )/(2)`   and  the same  current  is passed  through  it what is the  ratio of the   magnetic   moment  of the  new coil  and the   original coil ?