Crystal Creator! Testing the Resistance of Crystals
Students create crystalsCopyright 2022 Aerielle Rodriguez, Rice University RET
Lab-designed crystals are a unique method to introduce students to a wide range of basic engineering principles. In this activity, students create large, single crystals using the slow evaporation method to grow insulators with different band gaps—an energy range in a solid where no electronic states can exist—
and, therefore, different resistances. Students then test how resistance is affected by temperature for insulators as well as for conductors. In the process of testing resistance, students learn how optical properties affect a material’s electrical properties and chemical composition.
Engineers must determine the best material to use for given situations. For example, engineers need to know how conductive a material is as this particular property will affect a material’s performance. Engineers determine which conductor or insulator they should use for the different parts of a particular device based partly on the resistivity of that material. If the resistivity can be altered to be more efficient at its job simply by changing the color or opacity of the material, this could have important implications for how the material is used.
After this activity, students should be able to:
- Create a saturated solution.
- Describe why insulators and conductors have their properties in terms of electron movement.
- Graph the effect of temperature and solubility.
- Discuss the effect of temperature on the resistance of insulators and conductors.
- Explain how the wavelength of light affects electron energy.