Answer:
1/2
Explanation:
A toroid is a conducting wire through which a current flows through coils wrapped on a toroidal support. It has a magnetic field inside that is formed by concentric circles. Outside of it, the field is null.
The field is not uniform, as it is strongest near the inside of the ring and weakest near its outside. All this means that if r is the radius of the transformer, the magnetic field decreases as r grows larger.
