science

Liquid crystal thermometer

Liquid crystal thermometer is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Liquid crystal thermometer rather than just read about it. In short: A liquid crystal thermometer, temperature strip or plastic strip thermometer is a type of thermometer that contains heat-sensitive (thermochromic) liquid crystals in a plastic strip that change colour to indicate different temperatures. Liquid crystals possess the mechanical properties of a liquid, but have the optical properties of a single crystal.

Key takeaways

Liquid crystal thermometer belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Liquid crystal thermometer to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Liquid crystal thermometer from memory before moving on to harder problems.

Reference excerpt

A liquid crystal thermometer, temperature strip or plastic strip thermometer is a type of thermometer that contains heat-sensitive (thermochromic) liquid crystals in a plastic strip that change colour to indicate different temperatures. Liquid crystals possess the mechanical properties of a liquid, but have the optical properties of a single crystal. Temperature changes can affect the colour of a liquid crystal, which makes them useful for temperature measurement. The resolution of liquid crystal sensors is in the 0.1 °C (0.2 °F) range. Disposable liquid crystal thermometers have been developed for home and medical use. For example, if the thermometer is put onto someone's forehead, it will change colour depending on the temperature of the person's body. There are two stages in the liquid crystals:

the hot nematic stage is the closest to the liquid phase where the molecules are freely moving around and only partly ordered. the cold smectic stage is closest to a solid phase where the molecules align themselves into tightly wound chiral matrices. Liquid crystal thermometers portray temperatures as colors and can be used to follow temperature changes caused by heat flow. They can be used to observe that heat flows by conduction, convection, and radiation. In medical applications, liquid crystal thermometers may be used to read body temperature by placing them against the forehead. These are safer than a mercury-in-glass thermometer, and may be advantageous in some patients, but do not always give an exact result, except for the analytic liquid crystal thermometer which shows the exact temperature between 35.5 and 40.5 °C (96–105 °F). Liquid crystal thermometers are also commonly used in aquariums, in homebrewing, and in mood rings. The liquid crystal thermometer was invented by Bob Parker in California, one of many of the inventor's thermochromic applications patented in the 1970s.

References

Worked examples

Example 1 — a first encounter with Liquid crystal thermometer

Start with the simplest possible case. Write down what Liquid crystal thermometer claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Liquid crystal thermometer before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Liquid crystal thermometer ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Liquid crystal thermometer

In research: Liquid crystal thermometer appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Liquid crystal thermometer in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Liquid crystal thermometer is common in secondary-school and first-year university syllabi. It links to neighbouring topics Liquid crystals, Standards and measurement stubs, Thermochromism, so understanding it makes those chapters shorter.
In everyday life: Look for Liquid crystal thermometer outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Liquid crystal thermometer in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Liquid crystal thermometer means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Liquid crystal thermometer out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Liquid crystal thermometer in simple terms?

Why does Liquid crystal thermometer matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Liquid crystal thermometer?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Liquid crystal thermometer.