Thermal Conductivity [From NCERT]

• Unit =  1 W m⁻¹ K⁻¹ 

•  1 W m⁻¹ K⁻¹ = 6.938 Btu in/hft² °F

 Reference: NCERT Physics Page 210

• The constant of proportionality K is called the

thermal conductivity of the material. The

greater the value of K for a material, the more

rapidly will it conduct heat. 

• The SI unit of K is

J s^–1 m^–1 K^–1 or 1 W m⁻¹ K⁻¹ 

• Gases are poor conductors,

and have the low thermal conductivity of air.

• Houses

made of concrete roofs get very hot during

summer days because thermal conductivity of

concrete (though much smaller than that of a

metal) is still not small enough. Therefore, people,

usually, prefer to give a layer of earth or foam

insulation on the ceiling

NCERT