When a current-carrying conductor is placed within a ferrous cylinder, the magnetic field generated by the current in the conductor interacts with the material properties of the ferrous cylinder. Ferrous materials exhibit high magnetic permeability, which means they can easily become magnetized in the presence of a magnetic field.
As the current passes through the copper conductor, it produces a magnetic field around it. When this field encounters the ferrous cylinder, the cylinder's material responds by concentrating the magnetic field lines within itself due to its higher permeability. This results in an increase in magnetic flux density in the cylinder compared to what exists in the conductor.
Furthermore, the ferrous material channels or enhances the magnetic field, thereby amplifying the intensity of the magnetic field lines present in the cylinder. This phenomenon occurs because the ferrous cylinder effectively becomes a magnetic core, resulting in a greater magnetic field strength than that originally produced by the conductor alone.
In summary, the interaction between the copper conductor and the ferrous cylinder leads to a magnetic field intensity in the cylinder that is greater than that in the conductor itself.