question_answer

If in a circular coil A of radius R, current \[0.\text{75 at}{{\text{m}}^{\text{3}}}\] is flowing and in another coil B of radius 2R, a current 21 is flowing ; then the ratio of the magnetic fields\[{{B}_{A}}\]and\[{{B}_{B}}\]produced by them will be

A) 2                                             

B) \[\text{2}.\text{55 at}{{\text{m}}^{\text{3}}}\]

C) 3                                             

D) 1