Behavior of Charged particle in the magnetic field
When the charged particle moves through the magnetic field it experiences a force on it. When the charged particle q moves with the velocity v in the magnetic field B and the velocity of the particle is perpendicular to the direction of the magnetic field then force acting on it is given by F = q(v × B). Hence, the magnetic force is directed towards the circular motion of the particle and acts as a centripetal force. Thus if v and B are perpendicular to each other, the particle moves in a circle. Thus, the particle moves in the helical motion when the two components are acting perpendicular. When the particle moves along the direction of the magnetic field then no effect is felt upon it.
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.