A 10 mm cable is to be laid in an atmosphere of 20°C (ha = 8.49 W/m 2 K). The surface temperature of the cable is likely to be 65°C due to heat generated within. Find the rate of heat loss (a) with...

A 10 mm cable is to be laid in an atmosphere of 20°C (ha = 8.49 W/m²
K). The surface temperature of the cable is likely to be 65°C due to heat generated within. Find the rate of heat loss (a) with critical radius of insulation, (b) without insulation.