What does “Thermal expansion” actually mean in Thermal Properties of Matter, and why does it matter for JEE?
Most materials expand when heated because the average separation between particles increases. For an isotropic solid, area and volume expansion coefficients are approximately 2alpha and 3alpha when alpha is small.
In simple words: Most materials expand when heated because the average separation between particles increases. For an isotropic solid, area and volume expansion coefficients are approximately 2alpha and 3alpha when alpha is small. Getting Thermal expansion clear matters because JEE questions on Thermal Properties of Matter usually test this idea directly, not just a formula you memorised.
Key point
Thermal expansion
Common mistake
treating a hole in a heated metal plate as shrinking.
Memory tip
heat the whole drawing: the hole expands as if it were made of the same material.
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