Question

how does the strength of the magnetic field at the centre of the coil change if radius is doubled and current is also doubled

Answer 1

At the center of a current carrying coil, the magnetic field intensity is directly proportional to the current and inversely proportional to the radius of the coil. So, if the current is doubled and radius is halved, then the value of B increases by 4 times the initial value.

Answer 2

ANSWER:

At the center of a current carrying coil, the magnetic field intensity is directly proportional to the current and inversely proportional to the radius of the coil.

So, if the current is doubled and radius is halved, then the value of B increases by 4