Unit 10 Blog Post #3

Today in class, we started but just reviewing what reflection was. After a good review, we moved on to refraction. Refraction is the change in wave speed due to change in medium. The dependent for refraction is medium. A law involving refraction is Snell's Law. Snell's law in a basic equation is N1(sinO1)=N2(sinO2). We use this equation when a light shines through an object and bends. N is the index of refraction. N equals speed of light in a vacuum over speed of light in medium. This is written as N=C/V. When we know an angle of the light going in or out. Two rules we learned for when lights go through objects are:

When moving from slow to fast (medium), light will bend away from the normal.
When moving a fast medium to a slow medium, light will bend towards the normal.

After all that, we did a bunch of questions involving the Snell's law equation. Some problems went through regular object and some through triangle glass blocks making it a little more confusing. Mr. Blake then showed us how to do equations involving lens. He told us about how glasses fix the vision of people who are near or far sighted. We then drew light going through lens and where they reach. We learned two rays involved in these lens. The parallel ray is from the object to optic axis, thru lens and bends thru focal point to other side. The optic axis goes thru the center of the lens in our equations and where the object looking through lens is on.The focal point is from the object thru focal point on the object side thru lens, then parallel. The central ray goes from object thru the center of the lens then continues (no bending).

This is a picture of my friend Grant. Grant is far sighted. That mean the light doesn't reach all the way back of his eye like people who have 20-20 vision. The lens of the glasses get the lights to reach the back of his eye so he can see clear.