Blog 14: Colours

Pictured: not my foot

So I went over to my friend's house the other day to do some movie watching. Some of our other friends were also due to come over, so we sat outside and waited for them. While we were out there, my friend had the good idea to bring out food substances to sustain us. Her food substance of choice? Watermelon.

Now I'm not a particular fan of watermelon, but I am a fan of spitting, so we engaged in a seed-spitting contest. One of the things I do like about watermelon (besides the seeds) is the colour. The red-pink is just so cheery.

Physics time: why does red look like that? Actually, we're not sure about that. We can explain why things appear red, though.

Visible light has three colors: red, green, and blue. These are different from the primary colors we learn in elementary school. The colors we use to make the other colors in fingerpainting are red, yellow, and blue. That's because using pigments like paint to make colors is a subtractive way to make colors, and the red/yellow/blue combo is pretty similar to the magenta/yellow/cyan (and black) scheme used in printing, but I digress.

White light is comprised of "all" colors, which can be made from red, green, and blue. The watermelon (remember that?) appears red(ish) because the RGB light from the sun hits it, but the green and blue wavelengths are absorbed, and only the red is reflected to our eyes. The rind appears green because red and blue are absorbed, leaving only the green to reflect. Only blue is absorbed by the yellow part of the rind, yellow being the marriage of red and green. Finally, the black seeds appear such because all red, green, and blue wavelengths are being absorbed, so there's nothing to reflect back to your eyes.

It's like spitting little bundles of negative light. (Not really.)

blog 11: ALL ABOUT MAGNETISM!!!!1!!!1111etc

My assignment sheet says I'm supposed to blog about magnetism, so here I go. (Good of you to specify, Mrs. Chen.) I was going to talk about motors and car batteries, but... eh. Let's just do this.

another picture because it is required

oh look hello. it is my refrigerator. as you can see, we have many items posted on it by means of magic magnets. such items include winter ball photographs from i think last year and an announcement of birth from also last year and a report from my eye doctor and also a schedule for the chorus. there is also a christmas wreath that we put up i think in january and still haven't taken down.

on its own the refrigerator is not magnetized. if i were to hold a steel pin to it and let go the pin would fall to the floor and i would have to look for it for like twenty minutes or something because our kitchen floor has this weird pattern that makes finding small things triple hard. the magnets are, well, magnetic and also magnetized. they are permanent magnets and when they are on the refrigerator the bit of the refrigerator they are on is also magnetized.

So let's restore use of my shift key and talk a little more srsly about magnets, magnetism, and magnetizivitytyy. (I only said "a little more srsly.") As we're all aware, matter is made up of atoms (lit: "thingies"). Obviously I'm cutting corners here, but who cares? We got some subatomic particles, but the ones I'm interested in are electrons (lit: "negatively charged subatomic particles"). They are negatively charged! They also have spin (well, actually, it's more complicated than that, but let's just stay in kiddie land understanding. Deal? Good.) The spins of electrons mean they have their own little magnetic fields. In most materials, though, they come in pairs that cancel each other out. In magnetic materials (and here I am thinking mostly of ferromagnetic materials like my steel pins) the electron spins do not cancel, and we get domains. If a material doesn't have domains, then it isn't magnetic and it won't be magnetized no matter how you stroke it. Things like iron, nickel, and cobalt have domains. This doesn't mean that they are magnetized, though. If the domains are all willy-nilly, there's still no net magnetic field. However, it's possible to get the domains all lined up the same way (by, say for example off the top of my head, taking a magnet and stroking it in one direction). Once you do that, there is a net magnetic field. The temporary magnetic field and the permanent magnetic field attract each other, and the Winter Ball photographs stay up.