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Thermometers

Imagine you wake up one morning feeling icky. Oh no, you're sick! You go tell your mom. She says, "Let's check to see if you have a fever." Then she sticks some weird long thing in your mouth. After a few minutes, she looks at it. Then she says, "You had better stay home today. You have a temperature of 101°!"

What was that thing she put in your mouth? And how did she know how hot you were? Well, that something is called a thermometer (thur-mom-uh-tur). A thermometer is a device that measures how hot or cold something is. It is made out of a long glass tube with liquid inside of it. The glass has several numbered marks on it. These numbers are based on a temperature scale.

When the thermometer touches something hot, the liquid inside the glass moves up the tube. When it touches something cold, it moves down the tube. When the thermometer is just as hot or cold as the thing it is touching, it stops moving. The length that the liquid has moved up or down is the temperature of the thing it touched. The numbered marks tell you what that temperature is.

So, when your mom puts a thermometer in your mouth, she was finding out how hot or cold you were. Your body made the liquid in the thermometer rise. When it stopped rising, your mom read how long the liquid was according to the marks on the glass tube. The marks told her how hot you were. Cool, huh? Or maybe I should say "hot"!

Thermometers

Thermometers are devices used to measure the temperature of a substance. Most thermometers are known as "liquid-in-glass" thermometers. They consist of a liquid or gas in a glass bulb with a glass tube attached to one end. The glass tube has several marks with numbers on them that are based on a temperature scale.

The liquid (usually mercury or alcohol) in the bulb is free to move into the tube. When the thermometer touches something like the air, the liquid in the thermometer will grow or shrink. The liquid will stopping moving when it reaches the same temperature. The marks measure the length of the liquid and thus the temperature of the air!

Thermometers

Thermometers are devices used to measure the temperature of a substance. Most thermometers are known as "liquid-in-glass" thermometers. They consist of a liquid or gas in a glass bulb with a glass tube attached to one end. The glass tube is calibrated with marks based on a temperature scale.

The liquid (usually mercury or alcohol) in the bulb is free to move into the tube. When the thermometer is put in thermal contact with a substance, the liquid in the thermometer will expand or contract. The liquid will stopping moving when it reaches thermal equilibrium with that substance. The calibrated marks give the temperature of the substance based on the length of the liquid.

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