Principle

The expansion of an object due to temperature changes is called "thermal expansion".　Usually refers to the situation where the external pressure is constant, most substances increase in volume when the temperature increases, and shrink in volume when the temperature decreases. There are also a few substances within a certain temperature range, but their volume decreases when the temperature rises. Under the same conditions, the expansion of solids is much smaller than that of gases and liquids, and it is difficult to directly measure the volumetric expansion of solids. But it can be inferred from the fact that the shape of the solid does not change when the temperature rises. Generally speaking, the solid expands in the same direction in all directions. Therefore, the linear expansion of a solid in one direction can be used to characterize its volume expansion.

Overview

In this experiment, the sample copper tube and aluminum tube are heated by steam, and the micro elongation of the experimental sample is directly measured by a micrometer to realize a teaching experimental instrument for determining the linear expansion coefficient of metal. The instrument is composed of a steam generator, a metal sample tube, a temperature sensor and a small displacement sensor. It can dynamically measure the small change of the sample with a stable temperature drop, and two digital displays can display the sample temperature and small displacement in real time, and Digital sensors can be used to dynamically record displacement and temperature changes in real time.

Features

1. The visual design of the experimental device is convenient for students to understand the measurement principle of the linear   expansion coefficient. Equipped with a transparent acrylic protective cover, it can not only intuitively observe the working state of theexperiment, but also effectively avoid the risk of high temperature burns.

   

2. Directly adopt the national standard platinum resistance sensor PT100 to measure the temperature, and the temperature directly   reads, which improves the test accuracy and eliminates the errors caused by the low thermocouple accuracy.

3. A displacement sensor with a minimum accuracy of 0.001mm is used to measure the linear expansion coefficient (elongation) of the metal tube accurately.

4. Steam heating is adopted, which is convenient for experiment management, and safe and reliable;

5. Measuring medium: copper tube, brass tube, aluminum tube, relative error of measurement ≤5%.

6. Convenient data acquisition interface: The experiment power supply is equipped with two analog data acquisition interfaces, which   can be connected to voltage sensors and PASCO data acquisition software. It can collect a large amount of data in real time to   analyze the test results, and it is convenient, fast, and efficient to complete the experiment content.

Experimental Content and Typical Data

Experiment: Coefficient of thermal expansion of three different samples (copper, brass, aluminum)

Parts List

Metal Thermal Expansion Coefficient Tester BEM-5721

Metal thermal expansion coefficient test sample holder BEM-5723

Steam generator BEM-5724

Platinum resistance PT100 BC-101542

Displacement sensor 0-10mm BC-105242

Connecting wire, 0.8m, red BC-105084

Connecting wire, 0.8m, black BC-105083

Power cord BC-105075

User Manual CD-M-BEX-8105B

Digital Experiment Options

UI-5400    Capstone data acquisition software

PS-3211    Wireless voltage sensor　【2】