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: =1, =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 ($\mu_r$) 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 ($\sigma$) of the medium, where free charges move and collide, converting electrical energy into thermal energy. In such a medium, the electromagnetic