Light is everywhere around us. Not only does it help us see, but it also plays a key role in photography. In Physics terms, light is an electromagnetic wave that undergoes reflection, diffraction, refraction, and scattering, just like other waves.
When a light wave bounces back from the surface of a medium, this phenomenon is known as reflection. Refraction is the bending of light as it travels from one medium to another. Diffraction is the bending of light around the edges of an obstacle whose size is comparable to the wavelength of the light waves.
Light is a combination of electric and magnetic fields. In some cases, both the fields vibrate in different planes, and as a result, light propagates in a different direction. This type of light is called unpolarized light. Confining unpolarized to one plane is termed polarization.
Photographers use polarized lenses to take glare-free images. Chemists use it to identify the concentration and nature of substances in a chemical solution. The concept of polarization holds a special place in physics due to its huge application in optics. However, for educators, this process can be tough to explain and for students to learn.
Read on to explore three reasons why polarization can be tricky for students and five ways through which you can make it an approachable topic.
Physics is one of the interesting subjects in physical sciences due to its numerous applications in the real world. Despite that, some topics like polarization can be a little tricky for students, let’s explore the three reasons why that is the case.
Optics is the study of light. Students explore the path of light; how it travels, bends, and changes its paths across mediums. All these processes are visualized through ray diagrams of light. However, students find it hard to visualize and draw it on paper.
To study polarization, students need to have sufficient background knowledge of light, and its basic properties. There are mainly seven properties of light including reflection, diffraction, refraction, interference, dispersion, scattering, and polarization. To understand the behavior of light, these properties are quite important. However, at the same time, it is difficult for students to digest them in one go.
In the introductory Physics courses, educators usually don’t stress this topic. Moreover, they explain critical concepts like polarization without mentioning its applications. So, learning about this technique becomes monotonous because they don’t see its relevance in the real world.
Keeping in view the problems faced by students in understanding light, here are five ways you can adopt to make light and polarization an interesting topic.
Polarization is a very dry topic to discuss with students. To make it more engaging, you can share some interesting facts about the properties of light. Some surprising facts about light are stated:
Light travels at a constant speed of 299 792 458 meters per second. With this speed, one can travel around the Earth 7.5 times in a second!
As per Einstein’s relativity, no object can travel faster than light in a vacuum.
Plants turn light (sunlight) into food using the process known as photosynthesis.
Sir Isaac Newton found out that white light (sunlight) is composed of seven distinct colors. To separate light into its constituent colors, we pass it through a prism.
Light always travels in straight lines. However, the objects in the path, cause it to bend in different directions.
The color of an object is actually due to the color it reflects. For instance, a wooden box appears to us brown, because it reflects brown light.
The electromagnetic spectrum is huge. However, we humans can just see the waves that lie in the visible spectrum. Animals and insects can see more than our eyes can.
All other forms of energy (heat, electrical, chemical, etc.) are invisible. Light is the only form of energy visible to the human eye.
Optics is considered one of the difficult fields in Physics. Firstly, it involves an intricate diagram of how travels through different surfaces. Moreover, when covering complex topics like Polarization, background knowledge is of great significance.
Though some students may have an idea about the basics, it is always a good idea to start the lecture with simplistic terms. This not only clears the students’ misconceptions but also gives them a fresh start. If you directly move onto the main topic, it will be a little hard for them to digest.
When explaining polarization, do explain the following terms to students:
Electromagnetic Waves: Waves are the carriers of energy. The main classification of waves is on the basis of medium, which returns us to mechanical and electromagnetic waves. Mechanical waves require a medium to travel. For instance, sound waves travel through the air. Whereas electromagnetic waves don’t need any medium to travel i.e. radio waves, microwaves, x-rays, gamma rays, etc.
Figure: Different Types of Electromagnetic Waves in Labster simulation Light and Polarization.
In fact, we are surrounded by millions of waves. However, most of these are invisible due to wavelength. The waves which lie in the visible spectrum are called light waves.
Lightwaves: We all know that light is a form of energy emitted by luminous sources such as the Sun or an electric bulb. However, the important point to mention is that light is an electromagnetic wave i.e. a wave formed by the interaction of changing electric and magnetic fields. Both these fields are mutually perpendicular to each other and in continuous vibrations.
Unpolarized Light: Sometimes, these vibrations are in multiple planes. When that happens light propagates in multiple planes. Such light is called polarized light. Light from Sun, incandescent bulbs, and the flame is unpolarized.
Polarization: Confiningunpolarized light to a single plane is termed polarization. This is done by devices known as polarizers.
Students have difficulty learning the interaction of light, and how it bends across the two mediums. It would be a great idea if you could arrange some experiments to show light phenomena like reflection, diffraction, and interference.
You can take the help of animations to describe light’s path. For instance, you can set up an experiment, as shown in the figure.
Figure from Labster’s simulation on Light and Polarization, which shows how light from a source is reflected by multiple mirrors
Moreover, multiple prism experiments can be used to explain how light behaves when it travels from one medium to another.
Students aren’t usually interested in learning abstract topics like this until you cite real-world applications. When you mention these applications, they get a motive to take an interest and learn more.
Polarized Sun Glasses
Direct eye exposure to sunlight can cause severe vision problems. For instance, when sunlight reflects from a smooth surface like a flat road or snow, it produces glare in the eyes. This glare is not only annoying but also causes vision problems. So, to filter out that unpolarized light, polarized sunglasses are used. The polarized lenses not only reduce glare but also make the vision sharper. Polarized prescription lenses are also available in the market.
Photography
When taking images of a reflecting surface like windows, or water, photographers place a polarizer in front of their DSLR lens. The polarizer reduces the glare from the reflective surface and the image appears clearer and sharper.
Identification of Compounds
Polarization is extremely helpful in chemical industries for the identification of compounds. Some substances are known as optical active i.e. they bend the polarized light at different angles. This amount of rotation tells the chemist about the nature and concentration of a substance in the solution.
Stress Evaluation of Amorphous Solids
Polarizers are widely used in the materials industry in the stress analysis of glass, and plastics. The temperature and stress profiles are seen through specialized polarized glasses.
Explaining complex light paths and planes of polarization can be done easily through simulations. You can simulate the diffraction, reflection, and polarization of light. For students, the visual explanation will surely help in grabbing the concept.
Here’s where Labster comes in. At Labster, we develop interactive story-based and gamified simulations. Through our interactive, students learn in a fun way.
For the concerned topic, you can check our simulation on Light and Polarization. In this simulation, students meet Mr. Einstein who introduces them to the physics of light. Then, they learn what is light, and how it propagates across the medium.
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