Journal 5/2/16 Tell me how you think your life would be different if you weren’t able to see color. Objective Tonight’s Homework To learn about the different wavelengths of visible light p 482: 1, 2 Start notebook checklist

Color, Wavelength and Spectra Yesterday we investigated colors. So what is color? Color is part of visible light, one of the 7 kinds of light we talked about earlier in the week. Purple light is made of the shortest, highest energy waves. Red are the longest, lowest energy waves of light.

Color, Wavelength and Spectra The shortest light we can see with our eyes has waves that are about 400 nanometers long. 1 nanometer is 1 billionth of a meter long. This makes visible light waves very small indeed! Anything smaller than 400 nanometers is so small that visible light passes right through it and it will essentially be invisible. We can only see things smaller than this by bouncing electrons off of them.

Color, Wavelength and Spectra So where does visible light come from? As different elements are heated up, they emit light in very specific colors. We call these specific sets of colors “emission spectra”. With lots of different elements added together, we get hot things that emit pretty much every color of the rainbow.

Color, Wavelength and Spectra Most of the light that we see is white light, which is made of all the different colors of light put together. When light hits an object, the object absorbs most of the colors. The ones that it doesn’t absorb bounce off and eventually reach our eyes. So the “color” of an object is actually the light that’s bouncing off of it. So a leaf, for example, absorbs everything except green, which bounces off to our eyes.

Color, Wavelength and Spectra The colored filters from yesterday’s lab work under this same idea. A red filter blocks all light trying to go through it except red light. Since red is the only thing going through, anything on the other side only has red light hitting it. If the object absorbs this red, no light bounces off so we see it turn black. If the object bounces the red light, we see it look pretty much the same as it always does. If we put a red filter on top of a blue filter and try looking through, we’re only going to see black because together both filters block everything!

Color, Wavelength and Spectra Since light is energy, this explains a few things you see in everyday life. In the summer, black objects absorb pretty much all the light that hits them. Absorbing all this light makes them get hot. White objects, on the other hand, reflect almost all of the light that hits them. Since they’re not absorbing energy, they stay cool. This is why black objects get much hotter than white objects under the summer sun. If you have dark hair, you’ve surely noticed that in the summer your hair can get pretty hot!

Spring Notebook Checklist We’re only a week away from the end of classes, so it’s time to start organizing your notebook and work or your checklist. Mr. C. is going to pass out your checklist at this point. Your job is to have your notebook ready for him to check next Friday. Please note that he will be checking everyone’s notebook. To speed things up and keep yourself from having a grumpy teacher, you need to put everything in your notebook in order that the checklist says. If Mr. C. has to go hunting through your notebook to find things, you’re going to be docked points!

Exit Question Can an object reflect more than one color at a time? Yes No Ice cream!