A wire of 8 mm diameter at a temperature of 60°C is to be insulted by a material having k = 0.174 W/mK. The heat transfer coefficient on the outside ha = 8 W/m2 K and ambient temperature Ta = 25°C. The maximum thickness of insulation for maximum heat loss will be
1
15.25 mm
2
16.50 mm
3
17.75 mm
4
18.25 mm