Uploaded September 2019 | Updated September 2026, 3 weeks ago
Awesome optical experiments with water and oil!
Equipment: glass, water, vegetable oil, drawings.
Place a coin in a cup so that it isn't in your line of sight. Just add water, and the coin will appear! Draw two horizontal arrows pointing in opposite directions. Place an empty glass in front of them. Fill the glass with water – the arrows change directions! You can achieve an equally amazing effect by drawing diagonal stripes or a chessboard. Wow! Optics is awesome!
Refraction is a phenomenon by which a wave, such as light, changes directions when transitioning from one medium to another. Different light-transmitting media have different optical densities, and therefore light travels through them at different speeds. The higher a medium’s optical density, the slower light travels through it. Refraction is everywhere, and we perceive it as completely normal: you can see how a straw in a glass of oil “breaks” at the border between the liquid and the air. Due to its shape, a glass of water acts as a lens capable of flipping an image. This creates stunning optical illusions. The refraction of light at the boundary of two media creates a paradoxical visual effect: objects overlapping both media appear "refracted upward" in the denser medium, while a ray of light entering a denser medium “refracts downward.” This effect causes bodies of water to seem shallower than they actually are. The refraction of light through glass or water is perhaps the simplest and most obvious example of beam distortion, but the laws of refraction apply to any waves – electromagnetic, acoustic, and even ocean waves.
Safety precautions: None.
Awesome optical experiments with water and oil!
Equipment: glass, water, vegetable oil, drawings.
Place a coin in a cup so that it isn't in your line of sight. Just add water, and the coin will appear! Draw two horizontal arrows pointing in opposite directions. Place an empty glass in front of them. Fill the glass with water – the arrows change directions! You can achieve an equally amazing effect by drawing diagonal stripes or a chessboard. Wow! Optics is awesome!
Refraction is a phenomenon by which a wave, such as light, changes directions when transitioning from one medium to another. Different light-transmitting media have different optical densities, and therefore light travels through them at different speeds. The higher a medium’s optical density, the slower light travels through it. Refraction is everywhere, and we perceive it as completely normal: you can see how a straw in a glass of oil “breaks” at the border between the liquid and the air. Due to its shape, a glass of water acts as a lens capable of flipping an image. This creates stunning optical illusions. The refraction of light at the boundary of two media creates a paradoxical visual effect: objects overlapping both media appear "refracted upward" in the denser medium, while a ray of light entering a denser medium “refracts downward.” This effect causes bodies of water to seem shallower than they actually are. The refraction of light through glass or water is perhaps the simplest and most obvious example of beam distortion, but the laws of refraction apply to any waves – electromagnetic, acoustic, and even ocean waves.
Safety precautions: None.



![Chemical printing in 10 minutes
Chemical printing, or your favorite image on a postcard in 10 minutes
Equipment: sodium carbonate, citric acid, ammonium iron(III) sulfate, potassium hexacyanoferrate(III), beaker, cotton roll, watercolor paper, negative image, hair dryer.
Dissolve sodium carbonate, citric acid, ammonium iron(III) sulfate, and potassium hexacyanoferrate(III) in water to create a light-sensitive mixture. Use a cotton roll to apply this solution to a piece of watercolor paper, then cover the paper with a negative image and set the paper and negative under a lamp. After 10 minutes, remove the negative image and rinse the paper with water, then dry it with a hair dryer – you’ve made a cute winter postcard!
Under the influence of bright light, the iron(III) ions in the photosensitive mixture begin to actively enter an excited state. At the same time, they oxidize citric acid ions, resulting in the formation of a complex mixture of organic substances and iron(II) ions, with which potassium hexacyanoferrate(III) forms an insoluble blue compound:
Fe²⁺ + K₃[Fe(CN)₆] → KFe[Fe(CN)₆]↓ + K⁺
This compound is firmly fixed in the pores of the paper, so when rinsed with water, the blue pattern remains!
A similar experiment is included in the “Cyanotype” set from the MEL Chemistry subscription.
Warning: only under adult supervision. Chemical printing in 10 minutes](https://i.ytimg.com/vi/dcfAKVyYhtY/mqdefault.jpg)






