A length of wire carries plane current; it is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is
a) A quarter of its first value
b) Unaltered
c) Four times of its first value
d) A half of its first value
A length of wire carries plane current; it is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is
a) A quarter of its first value
b) Unaltered
c) Four times of its first value
d) A half of its first value










