Mirror, mirror on the wall… You wink with your left eye and your mirror image winks with the right. What an annoying copycat! Well, it’s not his fault – that’s how reflection works. We will learn all about it, but also show something even cooler – refraction
Reflection and Refraction
Sight is our dominant sense. Most of all information we receive is coming through our vision. That’s huge! But how do we see the world around us? It’s actually not only about our capabilities. Objects must have one important property to be seen: they must reflect light. Light is such a tremendous topic that there is special discipline devoted to studying it – optics. Optics is a part of the physics that studies the light – its properties and the behaviour.
So, let’s talk about two important behaviors of the light: reflection and refraction.
Reflection is a familiar concept. You look at any polished surface such as the mirror and you see your own reflection. An image is virtually identical, but it’s reversed in the front-back direction. There are two rays of light in play here, incoming and outgoing. Incoming ray hits the surface under a certain angle and then outgoing ray goes under that same angle in the opposite direction. That’s called Law of reflection.
While passing through more than one medium, the light will be refracted
Refraction, on the other hand, means bending of the light. Bending happens whenever light changes medium in which it’s traveling.
For example, moving from water to air would produce this behavior. That occurs because of the difference in the density of different mediums. Air is in the state of gas and molecules of gas are spread out so there is less chance of light hitting them. But let’s put water into the mix. Here, molecules are more packed and that means light moves slower through them. That speed with which the light moves through a certain medium compared to the speed in a vacuum is called refractive index.
Air, for example, has a refractive index of 1.0003, while water has 1.333. That means light moves much quicker through the air. When light moves from the air into the water it slows down and that makes it change direction.
The science behind the Light bending
In our experiment, a light went from the air through the water and then back through the air to get to the drawing. We explained that light refracts when it changes medium and what does that mean.
In this case, the water behaves like a magnifying glass. Light bends towards the center, narrowing until it gets to the one point which we call focal point. From the focal point, light rays switch direction so the left one goes to the right and the right one goes to the left. The result is that our drawing looks reversed!
Materials needed for the Refraction Demonstration:
You will need a glass of water, some drawings or a pencil and the paper
- Transparent glass or bottle
- Water
- Some drawings (or pencil and paper)
Instructions for Light bending:
For step-by-step instructions on how to conduct this experiment watch the video on the beginning of the article or continue reading…
- Draw some images you would like to test
- Pour water into a glass
- Put the image behind the glass and look at it through the water. What do you see?
What will you develop and learn by doing refraction experiment:
- Basics of optics
- What is reflection and Law of reflection
- What is refraction and refractive index
- Scientific method
If you liked this experiment and want more cool stuff to do, we recommend you continue your exploration of physics. We bet you would like to learn how to make a potato battery! Or try some amazing balloon experiments!
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