Unit 10: Light properties (reflection)

Today we learned a lot about reflection. The two main types of reflection are specular reflection and diffuse reflection. Specular is when the surface is relatively smooth compared to the wavelength of the wave. Diffuse is when the surface of the object is bumpy/rough when compare to the wavelength of the wave. This means when light reflects off of a specular object, the light reflects off of a mirror-like object in a single direction and when light reflects off of a diffuse object, the light reflects in all different directions. This is because of the law of reflection. The law of reflection states that the angle of incidence is equal to the angle of of reflection, relative to the normal. The normal is a force perpendicular to the surface, so when the surface is smooth, there is on normal, but when the surface is bumpy there are many different normals, and therefore many different directions the light is reflected.

Today we also did a lot of work on color and color mixing. This is not the same type of color mixing you do in art class, because that is with pigments. This type of color mixing is using light. here is the basic color chart to follow.

Complimentary colors (colors on oppos. sides) create white.

White light is light with all of the frequencies or, in other words, ROYGBIV. Objects reflect certain colros and absorb certain colors. For example, a blue shirt that you own is blue because the shirt was made to absorb all of the other colors and reflect blue. When there is a shadow, there is an absence of light because all of the colors are absorbed and therefore it is black. That is why, when you wear a white shirt, you reflect all of the colors, but when you wear black, you feel hotter because it absorbs all of the colors.

 Here are two pictures (above and below) of when we used blue, red and green projectors in class to mix the lights and make shadows. The picture above is of Mr. Blake and the picture below is of me.

The picture below is when we used lasers to experience how light reflects. You can only see the beams if the air is junk, so we sprayed stuff in the air so that we could see the laser beams. cool.