What do arches and eggs have in common? Both can be used to trick your mind with awesome illusions that we encourage you to try at home. Keep watching to learn just how easy it can be to trick your brain. Then, read below to learn the science behind these tricks.
Materials to Collect
- Paper (construction works best)
- Scissors
- Eggs
- Candle or matches
- Cup of water
Try it!
Arches
- Take two pieces of paper and cut out two arches. Make sure your arches are the same size and shape.
- Hold one arch directly above the other, and ask someone else which arch appears bigger (they should think the bottom looks bigger).
- Then, switch the arches so the one that was on the bottom is now on the top and ask again which arch appears bigger (they should think the bottom one looks bigger).
- You can keep switching the arches back and forth. No matter which one is on top, the bottom arch should always appear bigger.
Silver Egg
- Ask an adult to help you light a candle or a match.
- Hold your egg just over the flame, so the eggshell gets coated in soot. Make sure you do this step in a safe location, and protect your hands from potential burns.
- Dunk the egg into your cup of water and look through the cup at the egg. Does the egg look different?
What is the Science?
Arches
Our brains are not equipped with rulers. When we determine the size of something by looking at it, we are doing so by comparing the size of the object we are looking at to other things around it or other things we have seen before. When you are trying to figure out which arch is bigger, your brain is comparing the two arches against each other. The reason the bottom arch always appears bigger is because of the shape of an arch. The curved shape means that the bottom edge is shorter than the top edge. When you are looking at an arch stacked above another one, your brain is comparing the bottom edge of the top arch to the top edge of the bottom arch. This means that your brain interprets the bottom arch as bigger!
Silver Egg
Soot is hydrophobic. If you break that word down, we have ‘hydro’ meaning water, and ‘phobic’ meaning, basically, a fear of. If you put those words together, we get ‘a dislike of water.’ Soot does not like to be in contact with water! This means that when the soot-covered egg gets dunked in water, a thin layer of air forms around the egg because the soot is repelling the water. This thin layer of air affects the way light travels to the egg and then back to our eyes, creating a beautiful silver effect!
Ask Your Young Scientists
- Why do you think our arches keep appearing to change size?
- How can you hold the arches so that they look the same size as each other?
- How does our egg look in the water vs. out of the water?
- Do you notice any other changes in the egg other than the color-changing when we put it in the water?
More to Explore
- Try to figure out some other shapes, besides arches, that this illusion could work for too.
- If you have extra eggs after this experiment, you can try these other activities:
- Learn more about illusions here: Spooky Special Effects at the Haunted Mansion
If you try any of these experiments, we want to see them. Share your pictures and videos with us by using the #ScienceAtPlay and tagging @CTScienceCenter.
This content was made possible in part by the Institute of Museum and Library Services.
Aoife Ryle is a STEM Educator at the Connecticut Science Center. In addition to working with school groups, she works with our Teen Program, Overnights department, and shoots weekly science segments for WFSB. She has a degree in Bioengineering from the University of Maine and has a personal interest in the life sciences and engineering which makes bioengineering a perfect crossover.
Nick Villagra is a STEM Educator at the Connecticut Science Center, responsible for developing and delivering science experiences, including classroom lab programs, stage shows, and vacation camps. Nick holds a Bachelor of Science in Engineering from Swarthmore College. and has been a speaker at the New England Museum Association conference. Always looking to put a unique stamp on the Science Center’s offerings, Nick enjoys incorporating custom-designed 3D printed materials for students to interact with.
