[:PiraScheme#Thermodynamics: Table of Thermodynamics Demonstration]

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[:Demonstrations:Lecture Demonstrations]

Thermal Expansion of Metal Rods , 4A30.58

Topic and Concept:

Location:

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Abstract:

This can also be called expansion rods. A metal blue box with various rods of different materials.

Equipment

Location

ID Number

Metal blue box with rods

[:ThermoCabinetBayA3: TD, A3, Shelf #1]

4A30.58

Safety glove and glasses

Important Setup Notes:

Setup and Procedure:

  1. Choose a rod and place it on the holder.
  2. Connect the burner to the methane supply.
  3. Open the valve to let the gas flow, and light the burner using a match or lighter.
  4. Place the flame under the rod to heat it.
  5. Note the rate of expansion.
  6. Turn of the gas by closing the valve, and allow some time for the rod to cool.
  7. Carefully (using insulated gloves) switch out this rod for another one and repeat the heating process.
  8. Note that the rate of expansion for this different material is different from the first rod.

Cautions, Warnings, or Safety Concerns:

Discussion:

where L, A, and V are the initial length, area, and volume respectively when the material has temperature Ti. The Δ denotes the change in that quantity (final - initial). αL, αA, αV are the linear, area, and volumetric coefficients of thermal expansion respectively. Note that for the 2D and 3D cases, equating αA to αL2 and αV to αL3 is only valid for small expansions (or contractions) in isotropic materials.

This demonstration shows that different materials have different coefficients of thermal expansion. We have two different materials that start at room temperature and are heated to the temperature of the flame. Thus, ΔT is the same for all the rods You will see that the orange tip scale will move to the left at some rate. Then choose another rod in place of the previous one and heat it. The orange tip will move to the left at different rate.

our available materials with their respective linear thermal expansion coefficients in ascending order

Material

αL (x 10-6 K-1)

Kovar

5.5

Titanium

8.6

Cold-rolled steel

12.4

Nickle

13.0

Brass

18.7

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Videos:

References:

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