Answer the followings: a) Why does the thermal conductivity of solids decrease w
ID: 1635051 • Letter: A
Question
Answer the followings: a) Why does the thermal conductivity of solids decrease with temperature while that of gases increase with temperature? b) What is the basic difference between an Otto cycle and a Diesel cycle? c) How do the real gases differ from ideal gases? Under what conditions can real gases be considered as ideal? d) Why is the COP defined differently for a heat pump and a refrigerator while they work under same cyclic processes? e) Using the formula for efficiency of a heat engine, explain the term quality of energy.Explanation / Answer
In solids, liquids or gases any particle be it molecule, atom or photon keeps colliding with other molecules and atoms. The average distance of each free path or the average distance between two collisions is called the mean free path.
The mean free path of molecules in solids decreases as the temperature of the solid increases. Or the mean free path increases as the solid cools other way around.
BTW if it were a gas you know what happens at Absolute zero Kelvin. You get a perfect lattice structure with no vibrations. So you get super conductivity.
Thermal conductivity depends on the ability of the lattice vibrations to travel through the medium without any disturbance or collisions.
Thermal conductivity will decrease as mean free path decreases.
So, the thermal conductivity of solids decrease with temperature while that of gases increase with temperature.
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