- Increase in dimension of body due to increase in temperature is call thermal expansion
- Most of the solid material expand when heated
-Consider a rod of length L then for small change in temperature ΔT,the fractional change in length ΔL/L is directly propertional to ΔT
or ΔL=αLΔT --(3)
- constant α characterizes the thermal expansion properties of a particulaqr material and it is known as coefficient of linear expansion.
- for materials having no prefential direction,every linear dimension changes according to equation (3) and L could equally well represent the thickness of the rod,side lenght of the square sheet etc
-Normally metals expand more and have high value of α
- Agian consider the intial surface area A of any surface .Now when the temperature of the body is increases by ΔT ,the increase in surface area is given by
where αA is the coefficient of area expansion
-Similary we can define coefficient of volume expansion as fractional change in volume ΔV/V of a substance for a temperature change ΔT
as ΔV=αVVΔT ----(5)
- K-1 is the unit of these coefficents expansions
- These three coefficent are not strictly constant for a substance and these value is depends on temperature range in which they are measured.
Relation between volume and linear coefficient of expansion for solid materail: Consider a solid parallopide with dimension L1,L2 and L3
then volume is
when temperature increase by a amount ΔT then each linear dimension changes and then new volume is
if ΔT is small the higher order can be neglected.Thus we find
Comparing this with equation (5) we find
Class 9 physics notes on chapter motion is now available at the following link CLASS 9 MOTION NOTES (FULL LENGTH)
Question1: A charge Q is divided in two parts q and Q - q separated by a distance R. If force between the two charges is maximum, find the ...
Coherent sources are those sources of light which emit continous light waves of same wavelength , same frequency and are in same phase or h...
Our New Free physics ebooks (pdfs) are available at this link . Hope you lile them.
Unit I: Physical World and Measurement (Periods 10) Physics: Scope and excitement; nature of physical laws; Physics, technology and society...
ADVANTAGES The generation of A.C. is cheaper than that of D.C. A.C. machines are simple , robust and do mot require much attention for the...
Hi all here in this article i am giving some tips and tricks to solve problems in mechanics. To master problem solving skill you need to pra...
1.A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x i...
Many times i have had users ask me a question which book to opt between H.C Verma Concepts of physics and NCERT physics books . My answer ...
Unit I: Electrostatics (Periods 25) Electric charges and their conservation. Coulomb’s law – force between two point charges, forces betwee...