A hollow square box is made from 1ft^2 sheets of a prototype insulating material that is 0.75 inches thick. A 120W electrical heater is placed inside the box. Over time thermocouples attached to the box show that the interior and exterior surfaces of one face have reached the constant temperatures of 150 degrees and 90 degrees. What is the thermal conductivity?

I am struggling with this question. Part a and b

A heating element made of tungsten wire connected to a large battery that has negligible internal resistance. When the heating element reaches 80.0°C, it consumes electrical energy at a rate of 480 W. Assume that the temperature coefficient of resistivity has the value given in Table 25.2 in the textbook and that it is constant over the temperature range in this problem. In the equation R(T) = Ro [1 + a(T - To)] take To to be 20.0°C. Part A What is its power consumption when the temperature of the heating element is 110.0°C? Express your answer with the appropriate units. P = Submit Value Provide Feedback Request Answer Units ?