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LINEAR
EXPANSION Expansion
in length of solid bodies on heating is called linear expansion. FACTORS
ON WHICH LINEAR EXPANSION DEPENDS Consider
a metallic bar of length "L1" at temperature
"T1" k .Let the bar is heated to "T2"
k.
From
experiments it is observed that linear expansion depends on two factors:
2.
The increase in length is directly proportional to the change in
temperature.
Combining
(1) and (2)
OR ∆L
= α L1 ∆T
Where
α=
Coefficient of linear expansion of solid. FINAL LENGTH OF BAR
From
figure:
L2=L1+∆L Putting
the value of
∆L L2 =
L1 +
αL1
∆T............ Where [
∆T= T2 - T1] COEFFICIENT OF LINEAR EXPANSION It is a
characteristic property of a material of solid and is defined as
"increase in length per unit original length per Kelvin rise in
temperature is known as coefficient of linear expansion". It
is denoted by "
α"
(alpha). Value of
α
is constant for a given
material but different for different materials. It is independent of
mass & dimensions of body . coefficient of linear expansion depends
on the nature of material. UNIT OF
α:
1/K |
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