Physics is a science with has brought plenty of applications in our daily life. And even despite the fact that as a school lesson it looks like Chinese arithmetic to many people, in fact it is not that difficult to understand! Just one small and simple experiment, such as the one presented in this post, which anyone can do at home, not only will surprise you with its results but will also demonstrate and help you better understand some of the basic physical laws.
You will only need is a simple piece of paper in which two arrows pointing in the same direction are designed. Place a transparent glass in front of it, and the image will not show any change, of course. However, if you fill the glass with water up to the height of the first arrow, you will see the arrow reversing and pointing in the opposite direction just like if it was some kind of magic!
Yet, this experiment has nothing to do with magic tricks. What we see takes place due to the phenomenon of refraction of light, which causes the reversal of the direction in which the beam of light is moving when passing through different materials (air and water).