Demonstrating Heat Energy
Materials:
- 1 balloon
- 1 air pump
- Tape measure
- 1 ice tray
- Water
- 1 mercury thermometer
Instructions:
1. Take your balloon and pump it with air using the air pump. If you are good at blowing balloons, you can try blowing air into it, too. Fill it up to a medium size and seal it. Measure its size with your tape measure and take note of the measurement.
2. Fill an ice tray with water. Place it in your freezer.
3. Place your balloon in your refrigerator.
4. Give both your ice and your balloon an hour in the freezer and refrigerator. In the meantime, go to one of the lamps in your home. Take your thermometer and touch the metal part onto the light bulb for thirty seconds (you can count the thirty seconds out loud.) Record the temperature you see on your thermometer, even if there was no change.
5. Next, turn on the lamp. Wait about twenty minutes, and then touch the thermometer to the light bulb again. What happens to the thermometer?
6. If an hour has passed, check on your ice tray and your balloon. What has happened to the balloon? Measure your balloon again and take note of this measurement. Is the water turning into ice yet?
7. Take your balloon and put it near your lamp, not close enough that the balloon is touching the bulb. You can situate the balloon right by your lampshade. Turn on the lamp and leave it on for two to three hours.
8. When you come back to your balloon, what has happened? Measure the balloon again and record the measurements.
This experiment is a demonstration of heat or thermal energy. In the experiment with the thermometer and the light bulb, the thermometer's reading rises when you touch the metal part to the light bulb because the atoms in the mercury are heated, they become excited and expand, thus causing a higher reading. In the experiment with the ice tray and water, you may or may not have started forming ice yet (depends on how cold the freezer is), but there should be a change in water temperature. This is because the freezer is cold and it's making the molecules in the water calm down or stop moving. When ice is formed, the water molecules are completely still or are frozen.
Finally, the balloon experiment demonstrates both properties. When you fill up the balloon with air, the temperature of the air inside it is at equilibrium with the air outside. When you put it in the refrigerator, the air molecules are forced to be less active because they are being cooled down, and so your balloon shrinks. Putting your shrunk balloon next to your lamp heats up the air inside the balloon again, causing the molecules to move about, expanding the balloon.
Next Article: Electric Energy
