Science Fact 4-Thermal Expansion

Thermal Expansion is the increase of the objects size by heating.
According to the particle theory, thermal expansion happens because particles have weaker attractive forces when heated so that the expansion occurs.
In daily life, thermal expansion happens because the object is heated until it expands a little bit.
From the 3 states (solid, liquid and gas), gas is the fastest to expand since its particles have very weak attractive forces.
There are 3 types of thermal expansion:(solid)
1.Linear Expansion
2.Area Expansion 
3. Volumetric Expansion

1.Linear Expansion:
-Occurs on 1D (one dimensional) objects such as wires and cables.
-Pattern:
Lt=Lo[1+α*(T-To)]
desc:
Lt= final length of the object  (cm/m)
Lo=initial length of the object (cm/m)
α=coefficient of linear expansion (°c/°k)
T=final temperature (°c/k)    l
To=initial temperature(°c/k) l --- Can be written as  ΔT (delta T)

2.Area Expansion:
-Occurs on 2D objects such as plates
-Pattern:
At=Ao[1+β*(T-To)]
desc:
At=final area of the object (cm²/m² )     
Ao=initial area of the object(cm²/m² ) 
β=Coefficient of area expansion (2α)
T=final temperature
To=initial temperature

3.Volumetric Expansion:
-Occurs on 3D objects such as cubes and cuboids
-Pattern:
Vt=Vo[1+ɣ*(T-To)]
Desc:
Vt=final volume of the object (cm³ /m^{3)
Vo=initial volume of the object}  (cm³ /m³⁾
  
ɣ=coefficient of volumetric expansion(3α)
T=final temperature
To=initial temperature

Thermal expansion of liquids:
 -One example is water anomaly
-Water anomaly is the unusual water behavior that first contracts to 0°C, then it expands below to 4°C again. 
-Only happens to water.

^{The graph of water anomaly.}

^{this is why fish can live in water during winter.}

Thermal expansion in gas:

-When you blow a balloon, the gas expands so that the balloon can be big.

Thermal Expansion in daily life:
1.Bimetallic Strip:

From the image, there are 2 metals with different coefficients.
After being heated, they both expand. The one with bigger coefficient will expand faster than the other one.
The bimetallic strip will bend towards the metal with smaller coefficient.

2.Electric Wires:

The electric wires will expand during the day and contract at night. 
This is why we should never set the electric wires too tightly so that they won't break when contracting 
at night.

3.Train Railways:

The train railway is given some gaps so that it won't bend when expanding during the day.


4.Thermometer:

It does regular expansion because of the temperature change. 
We can tell the exact temperature with the thermometer.