How to Do the Light Total Refraction Trick?

The Zip Lock Bag Water Refraction is a simple and easy but amazing experiment. You can make the picture disappear by just putting the zip lock bag into the water. It does look like magic. 

 The required material can be found in every home. Most of you can do it right now if you want.
Age: 3+          Time: < 10mins

 Safety 

1. Be careful with the fragile glassware.
2. Adult supervision.

 Materials List 

• Ziplock bag
• A sheet of A4 paper
• Marker
• Beaker (containers)
• Water

 Instruction 

Step 1/4 – Cut A4 paper into the appropriate size, just to fit the size of the ziplock bag.

Step 2/4 – Use the marker to write a part of a number on paper, then put the A4 paper into the ziplock bag and then, seal it.

Step 3/4 – Write the next part of the number on the ziplock, put two parts together into a whole number.

Step 4/4 – Pour some water into the beaker (deep enough to submerge the picture). Put the picture in the water. When you look at the picture from the top, the part you wrote on the paper will disappear and you will only see the part you write on the zip lock bag. When the zip lock bag is taken out of the water, the part written on the paper will appear again.

 Troubleshooting 

Why I can still see the part that is written on the paper? 
—This experiment is all about refraction, so the position we look from matters. Make sure you look from the top and the ziplock bag should be placed as vertically as possible.

 Scientific Description 

Total internal reflection, in physics, complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the critical angle. In general, total internal reflection takes place at the boundary between two transparent media when a ray of light in a medium of higher index of refraction approaches the other medium at an angle of incidence greater than the critical angle. When we look at the water from the top of the beaker the total reflection will occur and the light will not enter our eyes, so the part written on the paper in the ziplock bag cannot be seen while the part written on the ziplock bag is not totally refracted so you can still see it. When we lifted the ziplock bag out of the water we can see two parts.

 Extensions 

1. There are so many ways to play this wonderful experiment. What creative picture combination idea can you come up with？Check out our Holloween idea refraction, in the hope that it would inspire you. 

2. Light refraction is a great topic for kids to explore. Check out what we have come up with this topic. 

Reversing Pic Illusion

Disappearing Coin

Beaker Disappear in the Oil

Invisible Glass Rod Trick