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Make A Spinning Valentine PDF Print E-mail
Written by Jennifer K Mahal   

You can put a little magic into your Valentine’s Day cards this year with a simple optical illusion. Two images become one when you spin these disk-shaped valentines, making a heart appear with an arrow or the word “Love” appear between “I” and “You.”

Have you ever seen the trick where there’s a bird on one side of a circle of paper and a cage on the other? When the disk is spun, the bird appears in the cage.

That is an example of a thaumatrope — a disk with a picture on each side and two strings attached. When the disk is twirled using the strings, the two images appear to become one picture.

Invented in the 1820s by a doctor named John Ayrton Paris, it was first used to demonstrate the idea of “persistence of vision” to the Royal College of Physicians in London.

Persistence of vision is the expression people use to describe what happens when your eyes see images flash rapidly. Images stay in your retinas for up to one tenth of second after you see them. Combine that with the way your brain likes to bridge the gaps between images (known as the phi phenomena), and you see two images as one if the disk moves fast enough. Basically, your brain gets fooled.

Thaumatropes are often thought of as the precursors to animation and motion pictures. In animation, the images flicker fast enough to create the illusion of movement.

To create an optical illusion valentine, you will need:

* White Cardstock

* An object with a round bottom to trace (cup, can, etc)

* Pencil

* Scissors

* Crayons and/or Markers

* Flashlight

* Hole Punch

* Rubber Bands

To do this optical illusion, you will need to use cardstock or another stiff piece of paper. Typing, copy, and construction paper will fold when the disc is spun, which makes it very hard to see the illusion.

Use your cup or can to trace a circle in the cardstock. Cut out the circle. On one side, draw and color a heart in the center. Turn on the flashlight. Place the card, heart-side down, on top of the light. You should be able to see the heart shining through the paper. The flashlight is being used as a light table, an artist’s tool that helps with tracing and drawing. Draw an arrow on the sides of the heart.

Punch a hole at the 3 o’clock and 9 o’clock positions. Thread a rubber band through each hole, looping it through itself to secure it. Put a finger through each rubber band. Twist the circle until it is wound up, then let it go. You should see the arrow and the heart as one image while it spins.

What’s fun about making these illusion Valentines is that you can use your imagination and get creative. We made one where two peas appear in a pod! One thing to note: with the arrow/heart Valentine, the orientation of the images doesn’t matter. However, you will need to flip most images in order for the illusion to work. For example, in the “I Love You” valentine, when looked at through the flashlight, the word “Love” should be upside down compared to “I “ and “You.”

Remember that the disc spins on a horizontal axis. You can check whether your image is placed the right direction simply by flipping the disc over from the bottom. If the image on the other side is right side up, the illusion will work correctly.

Discover more science and art at the Santa Cruz Children’s Museum of Discovery in the Capitola Mall. Learn more at www.sccmod.org.

Jennifer K Mahal, who writes children’s books under the name Jenni Kaye, is a volunteer with the Santa Cruz Children’s Museum of Discovery. She lives in Santa Cruz with her husband and two children.

Last Updated on Wednesday, 01 February 2017 00:45
 
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