Physics Unit 10

The picture above, in case you didn't know, is a picture of the sun. Now I know everyone who is reading this is asking themselves "why is there a picture of the sun?", and I, being the incredibly generous person that I am, will tell you. In this unit, we are learning all about light behavior (woohoo, light behavior!!). In class, we pretty much spent the whole time learning a lot of vocabulary, as well as all about the electromagnetic spectrum.

First of all, light is a transverse, electromagnetic wave, and doesn't need a medium. This makes sense, since light travels through space. The speed of light, when written as a variable is a lowercase c, and is 3 x 10^8 m/s. In other words, the speed of light is 300,000,000 m/s. A light year, on the other hand, is the distance light travels in one earth year. An interesting fact to think about, is that the only reason you can see anything, is because light is reflecting off the objects and going to your eyes. If the light didn't reach your eyes, you wouldn't be able to see anything.

Two important terms that we learned today are opaque and transparent. When something is opaque, that means that the object is impenetrable by light. Transparent, is the exact opposite of opaque, which means that it is penetrable by light and other electromagnetic waves. An example of the two terms is saying that glass is transparent to visible light, but your eyelids are opaque. In other words, light can go through glass, but can't go through your eyelids (thank goodness for eyelids!). 

Lastly, we learned about the electromagnetic spectrum, which is the range of different wavelengths based on types of known waves. The electromagnetic spectrum is based on ROYGBIV, with red as low energy, and violet as high energy. Frequencies, wavelengths, and energies govern the different wave properties. While I'm not going to go into detail of the amount of hertz each category has, I am going to list them in order from highest to lowest energy rays instead. First, with the highest energy rays are gamma rays, which are responsible for nuclear reactions and cosmic rays, not to mention The Hulk. After gamma rays, there are x-rays, which are high energy waves that can cause mutations in cells, skin burns, and cancer. X-rays are opaque to bones and transparent to skin and muscle, which is why we used to use them whenever we had to see if we had broken bones. After that, there are ultraviolet (UV) radiation, which is beyond the visible region of the spectrum. After UV radiation, there is the visible spectrum, which has frequencies that are visible to humans. This is a very small portion of the spectrum, however, and it makes me wonder about all the things that we aren't seeing (oooh, spooky, right? Nah, not so much, actually...). After that, there is infrared, which is in the region with frequencies just below the red. Infrared gives off heat energy and radiation, and its frequencies are most absorbed by water. After infrared, there is the energy that comes from microwaves. Microwaves have the same energy is used in speed guns, and wireless transmitters. Lastly, but definitely not least, we have the waves that come from radios and televisions, which give off the least amount of energy rays out of everything else. 

I thought I'd put another picture, because who doesn't like pictures of sunsets?