In this science experiment we will solve the mystery of why the water rises. You are going to
have to keep your eyes glued to the experiment and observe closely to figure it out. We will learn
about air pressure in the process. Lets try the Why Does The Water Rise Experiment.
- Candle and matches
- Pie pan or plate
- Juice bottle or clear glass container
- Food coloring
Watch Video: Why Does The Water Rise Experiment
Process Why Does The Water Rise Experiment:
1. Add enough water to fill the bottom of the plate.
2. Put 3 or 4 drops of your favorite color of food coloring into the water and mix it up.
3. Place the candle in the middle of the plate.
4. Light the candle. Give some thought to what a fire requires to burn. Its called the fire triangle
(oxygen, heat, fuel). If any one of these items are missing there will be no fire!
5. Take the glass and place it over the lit candle. Ask yourself what invisible gas is inside the
glass. What happens to the water level inside the glass? What happens to the flame on the
6. Repeat the experiment a few times. Use the scientific method to see if you can figure out why
the water rises.
The Science Behind Why Does The Water Rise Experiment:
The flame on the candle needs the gas oxygen to keep burning. Once we place the glass
container over the lit candle, the oxygen inside begins to get used up. Once all the oxygen has
been used, the flame will go out. However, there are still other gases remaining inside the
glass (nitrogen, argon, carbon dioxide, etc). But these gases have lower pressure inside the
glass when compared to the higher atmospheric pressure on the outside of the glass. This
higher atmospheric pressure from the outside pushes the water from the plate up and into the
One more thing is happening here to make the water rise into the glass. When we cover the lit
candle with the glass, it heats the air inside the glass. The heated air expands. As it expands it
comes out from under the glass container. You might observe some bubbles after you put the
glass over the candle. Thats the hot air escaping. Once the flame dies out, the air inside the
glass begins to cool down. As it cools, the air contracts inside the glass container. This
contraction pulls the water from outside on the plate into the glass. Now grab some friends and
do the Why Does The Water Rise Experiment.
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