Unit 10: Light and Color

Today we learned about light and color.In the last unit we learned that sound is a pressure wave, but in this unit we learn about light and that it is a electromagnetic wave. The electromagnetic spectrum is a range of all electro magnetic waves. Electro magnetic waves are transversal waves that are perpendicular to each other. Some things we have to know before I talk about the range, are vocabulary. Opaque means light cannot pass through and transparent is when waves can go through.

The lowest frequencies in the spectrum are radios, TVs and cellphone. Theses range anywhere from 500 KHz to 1000 KHz. Next level is microwaves. The frequency of microwaves is the resonance of water. The next level is infrared. Infrared literally means "below red". Infrared light is heat energy and radiation. This is used to sometimes detect people through walls for police. Then comes the visible spectrum, which means the RAINBOW! This includes ROYGBIV. The only light visible to humans is between 4x10^14 to 7x10^14 Hz. Red starting as the lowest frequency and longer wavelengths to violet, which is higher frequency with shorter wavelengths. red has the lower energy while violet has higher energy. After visible frequencies is the ultraviolet (above violet). This is also known as UV and has different types like UVA and UVB and this is given off by the sun. Ultraviolet is opaque to the ozone layer and glass. And finally, the highest frequencies are X- rays and gamma - rays. These can go through just about everything except bones.

As you can see in the picture above, I use Neutrogena sunblock with SPF 55 when I go out and play tennis. I use it mostly because it smells better than other sunblocks and isn't oily but that is besides the point. The main purpose for this is to protect my skin. Luckily for me I have a higher melanin in my skin because I don't burn as much, I just get really tan. Like it says on the bottle, it has UVA and UVB protection. The main use for sunblock is to literally block the sun. It makes your skin more opaque to ultraviolet light. COOL.