These laminated sheets of liquid crystal are temperature sensitive. The plastic sheets remain black except for a five-degree temperature range in which they display a series of colors that reflect the actual temperature of the crystal. Using sheets that change colors at different temperatures opens up a world of possibilities for experimentation. The material can be easily cut with scissors. Self-adhesive backing. Please note that the effects of temperature on each of the liquid crystals depend upon the ambient temperature of the surroundings.
LIQUID CRYSTAL SHEET, 20-25oC TRANSITION (68-77oF)
This liquid crystal sheet changes color at a transition point just about below room temperature. Depending on the ambient temperature of your room, this liquid crystal will change its color by the heat of your hand, an ice cube or a can of cold soda.
LIQUID CRYSTAL SHEET, 25-30oC TRANSITION (77-86oF)
This liquid crystal sheet is so sensitive that it can detect the heat print your hand leaves behind! Place your hand on a book for a few seconds, then remove your hand and place the liquid crystal sheet over the spot where your hand was located. Observe as the liquid crystal changes color and makes visible your hand's heat print. Or, simply touch the material and observe the print left by the heat of your hand.
LIQUID CRYSTAL SHEET, 30-35oC TRANSITION (86-95oF)
This liquid crystal sheet changes color just slightly below body temperature. Placing the sheet near a gentle heat source or warming it with your hands causes the liquid crystal to change color, indicating areas of differing temperature. Perfect for showing the effect of samples higher than room temperature, such as hot coffee and heat from a light bulb. Try holding a strip against your arm and observe your veins!
Sizes are approximate. Order by temperature range.
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Why do liquid crystals change color with temperature?
The long, cigar shaped, molecules of a liquid crystal align themselves into orderly flat planes. The molecules in each flat plane are oriented at a slight angle from the molecules in the plane below it. Eventually, as the stack builds up and each layer is off set by a slight twisting from the one below it, two layers will have the same orientation. The distance between these two aligned layers is called the pitch. When white light is directed at this stack of molecules, the wavelength of light equal to this pitch distance is reflected back. At cold temperatures the pitch is far apart; red light is reflected back. At higher temperatures the molecules move faster and the layers twist more, causing the pitch to become shorter, reflecting blue light. Each liquid crystal has only a few degrees of temperature where the organization is such that light is reflected back. On either side of this temperature range, all light is absorbed and the liquid crystal appears black.
This product will support your students' understanding of the Next Generation Science Standards (NGSS)*, as shown in the table below.
Suggested Science Idea(s) 4-PS3-2
| Elementary || || Middle School || || High School |
| 2-PS1-1 |
Students can use Liquid Crystal Sheets to plan and conduct an investigation to describe and classify different kinds of materials by their observable properties. 2-PS1-4
Students can use Liquid Crystal Sheets to collect data to construct an argument with evidence that some changes caused by heating or cooling can be reversed and some cannot. 4-PS3-2
Students can use Liquid Crystal Sheets to make observations to provide evidence that energy can be transferred from place to place by heat currents.
| || MS-PS3-3 |
Students can use Liquid Crystal Sheets s to apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer. MS-PS3-4
Students can use Liquid Crystal Sheets for an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of the particles as measured by the temperature of the sample. DCI-MS/PS3.A: Definitions of Energy.
The temperature is a measure of the average kinetic energy of particles of matter. The Liquid Crystal Sheets creates a beautiful thermal print when acted on by an object, such as your hand. Each color represents a different temperature.
| || HS-PS3-4 |
Students can use Liquid Crystal Sheets to plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (Second Law of Thermodynamics).
Students can place their hand on the Liquid Crystal Sheets to observe the transfer of heat energy to the surface of the temperature sensitive material. Each color represents a different temperature. MS-PS3-3
Each color represents a different temperature as students test a device that either minimizes or maximizes thermal energy transfer. There are three temperature ranges of sheets available for investigations. MS-PS3-4
Students can use the Liquid Crystal Sheets for an investigation to determine the relationships among the energy transferred by different objects. HS-PS3-4
Students can use the Liquid Crystal Sheets for an investigation to determine the relationships among the energy transferred by different objects.
* NGSS is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, this product.