Negative thermal expansion
Have you ever played with a balloon? When you blow it up, it gets bigger! But if you let the air out slowly, it gets smaller and smaller.
Well, some things do the opposite. When they get warm, they shrink! And when they get cold, they expand. This is called thermal expansion, and it happens because things heat up and get more excited, or cold and calmer, making the molecules inside either spread apart or come closer together.
But there are some materials that don't follow this rule. They actually get smaller when they get cold and bigger when they get warm! This is called negative thermal expansion. It might sound strange, but it happens because of the way the molecules are arranged inside.
Think of a bunch of marbles in a jar. If the jar gets warm, the marbles start moving around more and take up more space. But if the jar gets cold, the marbles start sticking together and taking up less space. This is what happens with materials that have negative thermal expansion.
One example of a material with negative thermal expansion is a special kind of rubber called "silicone rubber." When it gets cold, it actually gets stiffer and harder to bend, because the molecules are getting closer together. But when it gets warm, it gets soft and squishy again!
Scientists use materials with negative thermal expansion in all kinds of things, from space telescopes to car engines. It might seem strange, but negative thermal expansion is actually very useful!
Well, some things do the opposite. When they get warm, they shrink! And when they get cold, they expand. This is called thermal expansion, and it happens because things heat up and get more excited, or cold and calmer, making the molecules inside either spread apart or come closer together.
But there are some materials that don't follow this rule. They actually get smaller when they get cold and bigger when they get warm! This is called negative thermal expansion. It might sound strange, but it happens because of the way the molecules are arranged inside.
Think of a bunch of marbles in a jar. If the jar gets warm, the marbles start moving around more and take up more space. But if the jar gets cold, the marbles start sticking together and taking up less space. This is what happens with materials that have negative thermal expansion.
One example of a material with negative thermal expansion is a special kind of rubber called "silicone rubber." When it gets cold, it actually gets stiffer and harder to bend, because the molecules are getting closer together. But when it gets warm, it gets soft and squishy again!
Scientists use materials with negative thermal expansion in all kinds of things, from space telescopes to car engines. It might seem strange, but negative thermal expansion is actually very useful!