the field coil of a motor has a resistance of 2500 ohm at 15°C by how much will the resistance increase if the motor attained an average temperature of 45°C when running ? take the temperature coefficent as 0.00428/°c referred to 0°c .

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.