00:01
Okay, as per the question is circular coil is there, has a radius r and the current flowing into it is, it is i, okay? and another circular coil is b that has radius 2r and the current is 2i, okay? then the magnetic field at the center of the circular coil are in the ratio of.
00:23
So we have to find out b a and here b b, okay? so magnetic field of the coil a and magnetic field of the coil b.
00:34
So we know the formula of the magnetic field of the circular coil it is mu not by 4 pi, okay, and it is full circle and number of loop is 1, so it will be 2 pi, i divided by r, okay? so here, current is capital i and r is capital r.
00:53
So i am replacing i and r here, okay.
00:56
So it will be mu not divided by 4 pi, it will be 2 pi, i divided by r, okay? so it will be b...