Unit 10 - Light Properties (Refraction)

This is a simpler example of some of the stuff we did in class today. Mr. Blake had a laser like in this picture and put glass objects in front of it, with the lights off we could see how the light refracted when it had to travel through the glass. In this picture the light goes through glass and the water, maybe if I had held the laser a little farther away you would of been able to see how the light refracted

In class today we learned SO much! We continued our learning on unit 10 light properties but today we learned about refraction. The main concept that we learned today is snails law. Snells law states that when moving from a fast medium to a slower medium, light will bend towards the normal. It also states that when moving from slow to fast (medium) light will bend away from the normal. This concept was major when we looked at lots of problems involving mirrors, light sources, glass, water, and air. In these problems we had to draw diagrams and snails law was important for all of them. Snells law was important for these diagrams because by knowing the materials that the light went through you could figure out if the light is going from slow to fast or fast to slow, then you could figure out which way the light refracted or would bend. For these problems we also used the equation:
(n1)(sinangle1=(n2)(sinangle2). Critical angle is when n1 > n2 and when the light goes from slow to fast.  Total internal reflection is when the angle of incidence > critical angle.

N is the index of refraction, the ratio is n= c/v where c is the speed of light in a vacuum and v is the speed of light in the medium. Every material has a different index of refraction. For example water and ice have different index of refractions, air and air have the same index of refractions. N of a vacuum=1 , N of air= approx 1, n of water =1.33, n of glass is 1.5, and n of diamond = 2.42. Index of refraction don't have units.

We also learned about different types of rays. Parallel ray is from the object parallel to the optic axis through lens and bend through the focal point on the other side. Focal ray is from the object through the focal point on the object side through lens then parallel. Essential ray goes from the object through the center of lens then continue (no bending). You need to use all three of these rays when you are drawing ray diagrams with lens. For these diagrams you need to state it's characteristics like if its real or virtual, upright or inverted, and if its enlarged or reduced. You can tell if the image is real or virtual by if the rays are converging or spreading apart.