Thermomagnetic analysis of some old roof tiles

To design the solenoidal coil, which has the linear magnetic field gradient along its long axis, is descrived.Firstly the magnetic field within an ordinal solenoidal coil is calculated for various dimensions. Next,the modified coil mentioned aboveis designed. As has been weU known,the magnetic field intensity Hx at a point on the central axis of the solenoid is given by the following equation (for example, see Nagata,1961)