Disappearing Beaker
We’re going to bend light to make objects disappear. You’ll need two glass containers (one that fits inside the other), and the smaller one MUST be Pyrex. It’s okay if your Pyrex glass has markings on the side. Use cooking oil such as canola oil, olive oil, or others to see which makes yours truly disappear. You can also try mineral oil or Karo syrup, although these tend to be more sensitive to temperature and aren’t as evenly matched with the Pyrex as the first choices mentioned above.
Here’s what you need:
- two glass containers, one of which MUST be Pyrex glass
- vegetable oil (cheap canola brand is what we used in the video)
- sink
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My Kids Loved this experiment! Thanks Aurora!
Unbeleveble!!!!!!!!Super cool.If it wasn’t science it
would be magic.
once i did something like this with water. you put a glass cup into a bowl of water and it looks like there is a hole in the water.
Whoa! That’s SOOOOOOOOOOOO cool!!!!!!!!!!
-Charli(7th grader)
This was a great experiment. Although I didn’t have a typical “Pyrex” jar, we used a small jar that I have for making yogurt. It’s a six ounce heat tempered jar and instead of “canola” oil, we used peanut oil which is lighter in color. It worked great. My daughter was excited to see it worked. Wish I could’ve taken pictures!!!
Cool
When light goes through the air and then hits a glass surface at an angle, some of the light bounces and reflects off the surface and the rest goes through the glass but it bends as it moves through the glass. When light goes from air into glass, it slows down (it’s this change of speed that makes the light reflect and refract).
Every material has a specific “index of refraction” that is related to speed of light in the material. The higher a material’s index of refraction, the slower light travels in that material.
Cooking oil has about the same index of refraction as Pyrex glass (1.474), but different glasses will have different values for their index of refraction. Notice how I said ‘about the same’. You can see a ghostly image of the beaker inside because the beaker has internal strains embedded in the glass that slightly change the index of refraction at different locations. The index of refraction changes with temperature, so you might find that this demonstration works better on some days than others.
Why does the pyrex glass have the same index of refraction as the oil, is there something alike between them?
Also, what is the index of refraction / optical density of regular glass?
No – it’s just cooking oil you are working with.
do we need rubber gloves to do it
You can find them here.
Where can I get a Pyrex beaker?
Pyrex has the same index of refraction as the oil, which means your eye can’t tell the difference between the two visually because passes through both the same way. Look at the trading material for more info on this, and ask me lots of questions!
What is pyrex, and why does it work?
I love these experiments. Keep them coming
Oops! Looks like I missed a question – sorry about that!
As the index of refraction value increases, the optical density increases, and the speed of light in that material decreases. For a vacuum, the index of refraction is 1.0000 (lowest optical density), and this is where light travels fastest. The index of refraction values give us a way to measure of the relative speed of a light wave in a particular material or medium. If we know the relative speeds, we can predict which way light bends when moving from one medium to another. Does this help?
Hi! I asked these questions last week and I don’t see any answers to them. I am teaching to my high schooler so I am interested in giving him the correct terminology and science. Could you please answer the questions below? Thanks.
How does optical density affect the index of refraction (e.g. as in your chart)? Am I correct in remembering that the higher the optical density then the higher the index of refraction? OR am I really off-base here?
How does optical density affect the index of refraction (e.g. as in your chart)? Am I correct in remembering that the higher the optical density then the higher the index of refraction? OR am I really off-base here?
I found them here – you can also remove the markings with a razor and a few sprays of window cleaner.
Where can you get unlabeled pyrex beakers (like in your video)?
WOOOOOOOAAAAAAHHHHH! THAT IS AMAZING!!! I AM GOING TO TRY THIS!!!!
…
WOOOOOOOOOAAAAHH!!!
Ooooh aaaah. Very cool. Will try this. Thanks!
My eight year old son loves these experiments! We have done two so far and have balanced each with reading and researching about what actually occurred and why. He loved it. I think it really brings the learning alive and gives him a reason to want to learn something. So far so good. Thank goodness I found this!
Pyrex has the same ‘light-bending’ ability as oil (same index of refraction). You can read about other things that will work in addition to Pyrex in the reading download.
Why Pyrex?
What web browser are you using? Try Firefox if you have it installed. If not, try a different computer. Does it work now?
The video is not working
Whoa… that’s so weird how it works!