21. Answer in units of W/m · °C.

Question

A box with a total surface area of 1.66 m^2 and a wall thickness of 6.23 cm is made of an insulating material. A 11 W electric heater inside the box maintains the inside temperature at 22.3 °C above the outside temperature. Find the thermal conductivity of the insulating material. Answer in units of W/m · °C.

Answer 1

Assuming the power from the heater is equal to the rate of heat out of the box:

P = (kΔT/t)(A) conductive heat flux times area (conductive heat flow out) (t is thickness

k = tP/(kΔTA)

When substituting in, express t in meters

Please consider a tutor. Take care.