Wednesday 2/13

So today we did not have a snow day (depressing) but we did have physics!! We learned about defraction today which is a change in the direction upon transmission into a new medium if the wave changes speed or strikes the boundary obiquely (this means not eqal to 90 or 0 degrees, basically not perpendicular). Refraction can occur through different media, such as water, glass or air.

Mr. Wirth described a very handy analogy that would help us remember refraction. Imagine a line of soldiers marching from a road onto sand (a slower medium). As they approach the sand and begin walking across it the line will bend. Wavefronts also bend and get closer.

The rules for refraction as follows:
1. If the speed decreases at the interface than the wave bends toward the normal; it forms a smaller angle with the normal.
2. If the speed increases at the interface than the wave bends away from the normal; it forms a larger angle with the normal.

The absolute index of refraction is a ratio of the speed of light in a vacuum to the speed of light in a medium, because it is a ration it is dimensionless. The reference table can be used for a particular frequency. Its symbol in n and the equation is n=c/v. Another equation used when there is two different mediums is n2/n1=v1/v2=wavelength1/wavelength2.

ALSO....we learned tody that Jess Dulski's father is a dentist. If your having problems with your teeth or think you may have a cavity contact Dr. Dulski immediately.

Julia Davis is also a champion sudoku player. She spends her time in class perfecting her skill so for fuure reference DO NOT interrupt her when she is trying to complete her sudoku puzzles. ( This should also be followed when she is applying her make-up. she has to look beautiful for her fans)

But anyways..BAGELS IN 2 DAYS AND BREAK!!!

2-12-08 class

Wavefronts and Rays
-use a ray to indicate the direction of motion of a wave front
-rays of a circular wavefront are radial lines
-rays on a plane wavefront are parellel lines
-use to track the direction of waves

Reflection
-a wave striking a surface at an angle
-latin "a bending back"
-the change in direction of a wavefront at an interface between 2 differences media so that the wavefront returns to the medium from which it originated

Law of Reflection
-angle of incidence= angle of reflection

Types
-law of reflection is always obeyed
-Specular-smooth surfaces, produces image of the source ex. mirrors