Ampere’s Circuit Law
The line integral of the magnetic field in a closed path is equal to the μ0 times the net current passing through that closed path or loop.
Magnetic Field on the Axis of a Circular Current Loop
Moving charges is an electric current that passes through a fixed point in a fixed period of time. Moving charges are responsible for establishing the magnetic field. The magnetic field is established due to the force exerted by the flow of moving charges. As the magnetic field is established moving charges start acting like a magnet.
Magnetic Effect of Current when current is flowing through the conductor, a magnetic field is established around it. This phenomenon is called the magnetic effect of electric current.