Determine the thermal conductivity for the insulating material if a 25.0W bulb is used to heat the box. The bulb maintains the inside temperature at 10.0ºC higher than the outside temperature.

A 3/16 in. thick acrylic testing box with dimensions of 10.0 in. x 10.0 in. is covered with an unknown 0.50 in. insulation material. Determine the thermal conductivity for the insulating material if a 25.0W bulb is used to heat the box. The bulb maintains the inside temperature at 10.0ºC higher than the outside temperature.