Two circular coils have diameters `10cm` and `20cm` with same number of turns. The ratio of the magnetic field induction produced at the centre of the coils when connected in series is

A circular coil of 200 mm diameter is made of 100 turns of thin wire and carries a current of 50 mA. Find the magnetic field induction at the centre of the coil.

Two current carying circular coils A and B, having the same number of turns are connected in series. What is the ratio of the magnetic inductions produced at their centres, in the diameters of A and B are 10 cm and 20 cm respectively ?

Two circular coils of radii 10 cm and 40 cm and equal number of turns are connected in series to a battery. The ratio of magnetic fields at their centres is

Two circular coils of radii 10 cm and 40 cm and equal number of turns are connected in series to a battery. The ratio of magnetic fields at their centres is

A wire of certain length carries a steady current. It is first bent to form a circular wire of one turn. The same wire is bent to form a circular coil of three turns. The ratio of magnetic induction at the centre of the coil in the two cases is ________