Am of this experiment is to study the magnetic field due to electric flowing through the coil. We need very simple apparatus for that. Inciliated copper wire 24 gauge which is available in the market. Connecting wires 12 boards batteries, cardboard or plastic sheet and iron filings. Now we make a coil of 20-25 rounds of copper wire around a hollow tube. We arrange the cardboard or plastic sheet as shown in the figure. Spread some iron filings on the cardboard. Connect both ends of the coil to the battery and switch on the electric current. Keep fickling fingers gently on the cardboard and observe the arrangement of iron filing. Increase the current in the circuit gradually and observe what changes occur in the arrangement of iron filings. When electric current starts flowing through the coil, magnetic field lines are produced at each point on the coil. They are circular in nature. As we go away from the wire, the concentric circle representing the magnetic lines of the force will become further apart. That is the distance between two circles goes on increasing. As intensity of electric current increases, the magnetic lines of force become clearer. What conclusion can be drawn? There are two conclusions. If the electric current flows through the coil, then concentric circles of magnetic field lines are produced at each point of the coil. In the above experiment, the intensity of magnetic field at any point by current flowing through a coil is depend on electric current going through the circuit.