CBSE - XI Science - Physics - Thermal Properties of Matter
Thermal Physics Urgent doubt
The expansion in length is called linear expansion. The expansion in area is called area expansion. The expansion in volume is called volume expansion.
Linear expansion - l/l a1 T
Area expansion - A/A 2 a1 T
Volume expansion - V/V 3 a1 T
The coefficient of linear expansion is denoted by the letter 'a' .
Where l = original length
The coefficient of linear expansion is a characteristic property of the material of the rod.
Expansion in area of a Laminar surface due to heating is known as superficial expansion.
Let a1 = area of a surface
t1 = its initial temperature
a2 = area of the surface after heating
t2 = final temperature
The coefficient of superficial expansion is defined as the ratio of increase in area to its original area for every degree increase in temperature.
Increase in area = a2-a1
Rise in temperature = (t2-t1)
Coefficient of superficial expansion (b)
Increase in volume of a solid on heating is cubical expansion.
Let V1 = Initial volume at t10C
V2 = its volume at t20C (t2>t1)
Then increase in volume 'v' = v2-v1
Increase in temperature 't' = t2-t1
The coefficient of cubical expansion is defined as the ratio of the increase in volume to its original volume for every degree increase in temperature. It is denoted by 'g'.
We can show that g = 3a
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