Sept. 28- Oct. 2

On Monday, we finished the testing that we started on Friday. The experiment from Friday was the reflectivity test, and we shined the lasers on the objects we were testing and observed how well the laser was reflected. My prediction was that none of the objects would reflect as well as the mirror. The objects I tested were a notebook cover, water, the dry erase board, and a mirror. When I reflected the laser off the notebook cover, the dot on the cardboard was big and dull. When I tested the dry erase board, the dot was smaller and less dull than with the notebook. When we tried to test water, it didn't reflect, the laser just passed through it. The mirror had the smallest and brightest dot out of them all. The conclusions we made were these: surfaces did vary in reflectiveness; "shiny" surfaces are more reflective; light passes through and is reflected off of glass; light spreads out on rough surfaces; and white reflects more while black absorbs more.

The experiment we had to finish on Monday had to do with light rays from the laser all going in the same direction and staying like that when they reflected off the mirror. The test was this: shine the laser at a mirror and clap erasers so that we could see the beam. My prediction was that the laser beams will be reflected in a straight line, and we would be able to see it with the erasers. When we did the test we observed that the beam looked like it did when we just shined it normally. Our conclusion was that the beams do go in a straight line when it hits the mirror.

After we discussed that experiment, we started talking about the angles at which the laser hits and reflects off of the mirror. The hypothesis was that the angle at which the laser hits the mirror will be the same as the angle at which the laser bounces off the mirror. The test was that we would hold up a clear plastic protractor vertical on the mirror and shine the laser through it at the measurements we were testing. The laser bounced back through the protractor and we could see what angle the laser was at. The IV was the angle at which the laser hit the mirror, or the angle of incidence, and the DV was the angle at which the laser reflects off the mirror, or the angle of reflection.

One night for homework, we had to make an analogy about light. Mine were these:Laser is to mirror as bouncy ball is the wall, and light is to wall as lots of really tiny bouncy balls are to wall. Then we started talking about the particle model of light. The model says that light rays are actually particles. So far, we've figured out that the particles are really fast, they scatter on rough surfaces, the particles travel in a straight line, and the light particle are called photons. We also started talking about the photons and water, but I don't really get yet, so I'll write about next week when I understand it better.