Hey Science Fans!
Here’s another great activity that you can do at home to amaze your friends and family (and explore learning with your kids!)
Instructions
WATER LIFTING CANDLE DEMONSTRATION
Here’s what you’ll need:
Pan, plate, or flat-bottomed dish
Water (add food coloring to make the effect even more visible)
Tea light or small candle
Matches or lighter
Tall glass cylinder, drinking glass, vase, etc
Warning! This activity uses fire. Make sure there is an adult present to help!
What you do
Pour some water (colored water is best) into a shallow dish or pan
Place a candle into the dish
Carefully light the candle
Place the glass upside down over the candle.
Watch as the candle goes out. What happens to the water?
What’s happening?
The “Fire Triangle” outlines the three things required for fire to be present: oxygen, fuel, and heat. When one of those items is missing, a fire can not start. If one of those resources is used up, the fire will go out. By placing the glass over the candle, you limit the amount of oxygen available to the fire. When the oxygen in the glass is used up, the candle goes out.
The flame of the candle creates heat which warms the air inside the glass. As the air inside the glass warms, it expands - you probably noticed some air bubble leaking out from under the glass while the candle was burning. When the candle goes out, the air in the glass cools. As the air cools, it contracts. This creates an area of low pressure inside the glass - a partial vacuum. The air pressure outside the glass remains constant, pushing down on the water in the dish.
The area of high pressure (atmospheric pressure) pushes down on the liquid in the dish, forcing it to go into an area of lower pressure (the space inside the glass). When that happens, the water level inside the glass will rise higher than the water level outside the glass. When the air pressure inside the glass and outside the glass are equal, the water level stops rising.
Experiment!
Does the size or shape of the glass make a difference?
Does the temperature of the glass have an effect on the outcome?
Does the amount of water in the dish have an effect on the outcome?