Explain the following with reference to magnetostatics: (i) diamagnetic material; (ii) lossy media. State three methods of electromagnetic shielding. State the ponyting's theorem. A 180 mHz plane wave travels in a medium characterised by: mur=1, r=20 sigma=2mS/m. Determine the: (i) loss tangent hence state type of conductor media; (ii) intrinsic impedance; (iii) attenuation constant; (iv) skin depth.

a) (i) A diamagnetic material is a type of material that is weakly repelled by an external magnetic field. In magnetostatics, when placed in a magnetic field, diamagnetic materials develop an induced magnetic moment that opposes the applied field. This results in a relative permeability (_r) slightly less than 1. All materials exhibit diamagnetism, but it is often masked by stronger forms of magnetism like paramagnetism or ferromagnetism. (ii) A lossy medium is a material in which electromagnetic energy is dissipated as heat as the wave propagates through it. This energy loss is primarily due to the conductivity () of the medium, where free charges move and collide, converting electrical energy into thermal energy. In such a medium, the electromagnetic