Circular Loop

Circular Loop We have so far observed the pattern of the magnetic field lines produced around a current-carrying straight wire. Suppose this straight wire is bent in the form of a circular loop and a current is passed through it. How would the magnetic field lines look like? We know that the magnetic field produced by a current-carrying straight wire depends inversely on the distance from it. Similarly at every point of a current-carrying circular loop, the concentric circles representing the magnetic field around it would become larger and larger as we move away from the wire (Fig. . ). By the time we reach at the centre of the circular loop, the arcs of these big circles would appear as straight lines. Every point on the wire carrying current would give rise to the magnetic field appearing as straight lines at the center of the loop. By applying the right hand rule, it is easy to check that every section of the wire contributes to the magnetic field lines in the same direction within the loop. Magnetic field lines of the field produced by a current-carrying circular loop Draw magnetic field lines around a bar magnet. List the properties of magnetic field lines. Why don’t two magnetic field lines intersect each other? We know that the magnetic field produced by a current-carrying wire at a given point depends directly on the current passing through it. Therefore, if there is a circular coil having n turns, the field produced is n times as large as that produced by a single turn. This is because the current in each circular turn has the same direction, and the field due to each turn then just adds up. Take a rectangular cardboard having two holes. Insert a circular coil having large number of turns through them, normal to the plane of the cardboard. Connect the ends of the coil in series with a battery, a key and a rheostat, as shown in Fig. . . Sprinkle iron filings uniformly on the cardboard. Plug the key. Tap the cardboard gently a few times. Note the pattern of the iron filings that emerges on the cardboard. Magnetic field produced by a current- carrying circular coil.