An electric kettle is required to heat 0.64 kg of water from 15.4°C to 98.2°C in six minutes. The supply voltage is 220 V and the efficiency of the kettle is 85.5%.
Assume the specific heat capacity of water to be 4.187 kJ/kg. K. Calculate the
resistance of the heating element.​

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk