Two wires of same length are bent to form the circular loop with two turns and a square loop of one turn. Both of them carry same current. The ratio of magnetic moment of circular loop of two turns to that of square loop is

The magnetic field at a distance 'r' from a long straight wire carrying current I is 0.4 tesla. The magnetic field at a distance 2r will be

In the cyclotron, as radius of the circular path of the charged particle increases, ($\omega$ = angular velocity, V = linear velocity)

The magnetic field at the center of circular coil carrying current '$I$' for a single turn of a given length of wire is '$B$'. The same wire is bent in a circular coil having two turns. When the same current passes through it, the value of magnetic field becomes