Measurement of thermal conductivity of a bad conductor (e.g. glass, cork)

• Glass s cut in form of a thin disc of cross section area, A and thickness, x.
• The disc is sandwiched between a steam chest and brass slab of mass, m and specific heat capacity, c.
• Steam is passed through the chest until the thermometers register steady temperatures, θ₁ and θ₂.

• The glass disc is removed, and brass slab is heated directly by steam chest, until its temperature is about 10⁰C above θ₁.
• Steam chest is removed, and the top of the glass slab is covered by the glass disc.
• The temperature of the slab is recorded at suitable time interval until its temperature is about 10⁰C below θ₁.
• A graph of temperature against time is plotted and its slope s determined at θ₁

Precautions

• Sample in a thin disc
• Faces of the disc highly polished to ensure tight uniform contacts
• A thin layer of grease is smeared on faces for good thermal contact.

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Dr. Bbosa Science