A length of wire carries a steady current I. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give double loop of smaller radius. If the same current I is passed, the ratio of the magnitude of magnetic field at the centre with its first value is:

Options

A. A quarter of its first value
B. Unaltered
C. Four times of its first value
D. A half of its first value

Answer

C