By Oleksandr Koliakin
THIS ARTICLE DISCUSSES LIGHT AS A WAVE!
Electromagnetic Waves
Electromagnetic waves are waves that travel at the speed of light. This section talks about the behavior of light as a wave, but remember, many scientists believe that light is a wave and a particle at the same time. Electromagnetic waves are transverse waves and do not need a medium to travel through. They were discovered by Heinrich Hertz (that's right, the units that were created to measure frequency were named after him, very modest). They are actually considered to be two waves traveling parallel to each other as shown in the picture below:
In this picture, the blue wave is the electric field and the red wave is the magnetic field. This may be confusing but luckily in this topic, we are mostly going to talk about the electric wave, or consider these two waves as one wave since the two waves are synchronized, which means they have the same frequency and amplitude.
If we consider these waves to be one wave for the reasons mentioned above, let's see what parameters tell us what about the wave. The amplitude is the brightness of the wave. Therefore, if the amplitude of the light waves you see is low, then the light appears to be dim. The frequency and wavelength of the wave tell us what kind of light we get. We can get radio waves (which have the longest wavelength and the lowest frequency), microwaves, infrared waves, visible light, ultraviolet waves, x-rays, and gamma rays (which have the shortest wavelength and the highest frequency). The frequency of the waves also tells us how much energy the wave carries, the higher the frequency the higher the energy.
Proof that light is a wave
The first piece of evidence that light is a wave is the Doppler Effect. Yes, the Doppler Effect isn't only valid for sound, but for light as well. The second piece of proof is a phenomenon known as wave interference. This is a unique property of waves is that if two waves pass through each other, they either add on to each other to make one wave with their combined amplitude or cancel out. This phenomenon is best observed in the Mach Zehnder experiment, which we will talk about later, so don't worry if you don't understand that yet. There is a lot of other proof that light is a wave, so you might have to keep revisiting this site to see more evidence.