question_answer

A circular coil ?A? has a radius R and the current flowing through it is I. Another circular coil ?B? has a radius 2R and if 2I is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of (i.e.\[{{B}_{A}}\] to \[{{B}_{B}}\])                              [CBSE PMT1993; AIEEE 2002]

A)    4 : 1                                  

B)    2 : 1

C)    3 : 1                                  

D)    1 : 1