Between glass air water and plastic what has the least thermal conductivity
Answers
Answer:
If you have 2 cups of equal thickness, one glass and one plastic, the plastic cup will insulate 5-10 times better than the glass cup, because the thermal conductivity of plastic is 5-10 times lower than than that of glass. ... This allows heat to transfer faster in glass than plastic
In simple terms this is a measure of the capacity of a material to conduct heat through its mass. Different insulating materials and other types of material have specific thermal conductivity values that can be used to measure their insulating effectiveness. It can be defined as the amount of heat/energy (expressed in kcal, Btu or J) that can be conducted in unit time through unit area of unit thickness of material, when there is a unit temperature difference. Thermal conductivity can be expressed in kcal m-1 °C-1, Btu ft-1 °F-1and in the SI system in watt (W) m-1 °C-1
. Thermal conductivity is also known as the k-value.
Coefficient of thermal conductance “ l” (kcal m-2 h-1 °C-1)
This is designated as l (the Greek letter lambda) and defined as the amount of heat (in kcal) conducted in one hour through 1 m2
of material, with a thickness of 1 m, when the temperature drop through the material under conditions of steady heat flow is 1 °C. The thermal conductance is established by tests and is the basic rating for any material. l can also be expressed in Btu ft-2 h-1 °F-1
(British thermal unit per square foot, hour, and degree Fahrenheit) or in SI units in W m-2 Kelvin (K)-1.
Thermal resistivity
The thermal resistivity is the reciprocal of the k-value (1/k).
1)Glass :1.05
2)Air (gas):0.024
3)Plastics, foamed (insulation materials):0.03
4)Water:0.58
5)rubber:0.13
Thermal conductivity is a material property describing the ability to conduct heat. Thermal conductivity can be defined as
"the quantity of heat transmitted through a unit thickness of a material - in a direction normal to a surface of unit area - due to a unit temperature gradient under steady state conditions"
Thermal conductivity units is W/(m K) in the SI system and Btu/(hr ft °F) in the Imperial system.
Air us the least thermal conductivity in the following materials.