1. Index of Refraction

2. The ratio of the speed of light in vacuum to the speed of light v in a given material is called the index of refraction, n of the material: n=c/v

4. If the light enters the medium where the speed of light is less, it bends toward the normal. If light travels from one medium into a second where its speed is greater, the ray bends away from the normal.

5. Snell’s Law

6. Total Internal Reflection

8. Important: total internal reflection can occur only when light strikes a boundary where the medium beyond has a lower index of refraction.

9. Total Internal Reflection: Applications

10. Thin Lenses

11. Any lens that is thicker in the center than at the edges will make parallel rays converge to a point and is called a converging lens. Lenses that are thinner in the center than at the edges are called diverging lenses because they make parallel light diverge.

12. Finding the Image Position Formed by a Thin Lens

13. -ray 1 is drawn parallel to the axis; therefore it is refracted by the lens so that is passes along a line through the focal point; -ray 2 is drawn on a line passing the other focal point F’ and emerges from the parallel to the axis; -ray 3 is directed toward the very center of the lens, this ray emerges from the lens at the same angle as it entered.

14. The Lens Equation Converging Lens: Diverging Lens:

15. 1.The focal length is positive for converging lens and negative for diverging. 2.The object distance is positive if it is on the opposite side of the lens from where the light is coming; otherwise it is negative. 3.The image distance is positive if it is on the opposite side of the lens from where light is coming. 4.The height of the image is positive if the image is upright and negative if the image is inverted relative to the object.

16. Lateral Magnification