A1.4. An electrical wire (diameter =3mm ) is insulated by a 2mm thick rubber cover [k=0.13W/(mK)]. The convection heat transfer coefficient at the outer surface of the cover is 15W/(m2K) and the temperature of the ambient air is 20C. a) If the temperature of surface of the insulation may not exceed 50C, what is the maximum allowable electrical power that may be dissipated per unit length of the wire? b) If the thickness of the insulation is increased above 2mm, will the heat transfer rate increase or decrease? Why? [15 marks]