Magnetic Field Strength (H) gives the quantitative measure of strongness or weakness of the magnetic field.
H = B/μo
Where
B = Magnetic Flux Density
μo = Vacuum Permeability
Magnetic Field strength at the center of circular loop carrying current I is given by
B = μoI/2r
B/μo = I/2r
H = I/2r
Where r = Radius
Now Given Parameters
Diameter = 1m
Current = 2A
∴ Magnetic field Intensity H = (2 / 2 × 1/2) = 2 A/m