When current is flowing in a circular loop of wire, the associated magnetic field at its centre is

When current flows through a circular loop of wire, it creates a magnetic field. The direction of this magnetic field can be determined using the right-hand rule. If you point your thumb in the direction of the current, your fingers will curl in the direction of the magnetic field.

At the center of the loop, the magnetic field is perpendicular to the plane of the loop. The strength of the magnetic field at the center of the loop is given by the formula:

B = μ0I / 2R

where:

• B is the magnetic field
• μ0 is the permeability of free space (4π x 10^-7 T m/A)
• I is the current
• R is the radius of the loop

So, the magnetic field at the center of the loop depends on the current flowing through the loop and the radius of the loop. The stronger the current or the smaller the radius, the stronger the magnetic field at the center.