Flag Modern Physics> Prove that beta equal 2 alpha and prove t...
question mark

Prove that beta equal 2 alpha and prove that gamma equal 3 alpha.

Grace , 6 Years ago
Grade 11
anser 2 Answers
Arun

Last Activity: 6 Years ago

Denote by 
α : the coefficient of linear expansion 
β : the coefficient of surface expansion 
γ : the coefficient of volumetric expansion 

Then a length increases as 

L → L ( 1 + α ΔT) 

But this means that for isotropic (same in every direction) expansion a surface (length x length) increases as 

A → A ( 1 + α ΔT)( 1 + α ΔT) ≈ A (1 +2 α ΔT) 
where we have neglected the (usually very small) square term (α ΔT)² . 

Comparing with the (definition of β) expression

A → ( 1 + βΔT) , we see the relation 

β = 2α . 

Likewise 

V → V ( 1 + γ ΔT) from the definition of volumetric expansion coefficient. 
But also we can approximate (volume = length x length x length) 

V → V ( 1 + α ΔT)³ ≈ V ( 1 + 3 α ΔT) , neglecting higher powers of α ΔT. 

Hence 
γ = 3 α
 
Hope it helps
Sai Soumya

Last Activity: 6 Years ago

You can find the answer in class 11 NCERT book in the chapter Kinetic Theory of Gases.
It has been briefly explained 
Otherwise you can refer to any reference book 
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments