How thirsty candle is rising water?

Burning candle raising water

Introduction

The result of the experiment is tricky to many people who wonder why a burning candle (we call it thirsty) makes water rising possible. Thus it is even more interesting for children who are totally amazed by the effect. Do you know what makes the trick? The pressure.

In our experiment we used:

Water
Food dye
Candle
Lighter
Vase
Vessel

Experiment execution

For the purpose of better visibility, we dye water.

Step 1 – Stabilize the candle

Use hot glue or wax from the candle to stick the candle into the bottom of a vessel.

Step 2 – Pour the water

Firstly, we pour the water into the vessel. Leave enough buffer so it will not spill once you put the vase into the vessel. Secondly, dye it with food dye on whatever color you like 🙂

Step 3 – Lit the candle

Once you have a water in the vessel and candle sticks well, you can lit the candle. Use methods convenient for you – matches, lighter etc.

Step 4 – Cover the candle with a vessel

Place a vase carefully over the burning candle (upside down!) and put it firmly in the vessel. It should stand good so you can observe the results relaxed.

Step 5 – Watch and relax

If you managed to get to this step you are ready for a reward. Just sit back and watch. The thirsty candle is burning, the water is rising higher and higher. Finally, the candle fade away and water is leveled up above its previous level.

Explanation for pros

We cover a burning candle with a glass vase. After several seconds the candle will go out and the water will be sucked into the glass vase, so the level of water will be higher in the vase than it had been before. It happens because burning candle needs oxygen. Due to the fact that there is a limited amount of oxygen in the vase, after several seconds the oxygen is used. The air pressure inside the vase is lowering therefore under-pressure is created. Additionally, higher atmospheric pressure pushes the water outside the vase and pumps it under the vase.

Interesting facts

Why does the water rise in the candle experiment?

It happens because burning candle needs oxygen. Due to the fact that there is a limited amount of oxygen in the vase, after several seconds the oxygen is used. The air pressure inside the vase is lowering therefore under-pressure is created. Additionally, higher atmospheric pressure pushes the water outside the vase and pumps it under the vase.

What will happen to a human in a vacuum?

He will lose consciousness after 15 seconds. This is the effect of sucking air from the lungs and depriving the blood of gases.
Sweat and saliva on the tongue will boil in the temperature of the environment (not 100 of Celsius).
The heart will stop due to oxygen deprivation after 60 seconds.

How do we know all this? From accidents. For example, in 1966 Jim LeBlanc tested one of the lunar suit prototypes in the vacuum chamber. During the test the air supply hose detached from the LeBlanc’s suit. After 10 seconds the pressure in his suit dropped to 0.007 atmospheric pressure.

Summary

Can you please find other examples where the under-pressure can be created?

Please leave the comment below. We are curious what are your suggestions and results.