ch15_bkes

Chapter 15 - REFRACTION

Useful Formulas for Chapter 15:  math n=\frac{c}{v} math math index\ of\ refraction=\frac{speed\ of\light\ in\ vacuum}{speed\ of\ light\ in\ medium} math
 * Index of Refraction**

**Snell's Law** math n_i=(sin \theta_i)=n_r(sing \theta_r) math math (index\ of\ refraction\ of\ first\ medium) x (sine\ of\ the\ angle\ of\ incidence) = (index\ of\ refraction\ of\ second\ medium) x (sine\ of\ the\ angle\ of\ refraction) math

**Thin-lens Equation** math \frac{1}{p}+\frac{1}{q}=\frac{1}{f} math math \frac{1}{distance\ from\ object\ to\ lens}+\frac{1}{distance\ from\ image\ to\ lens}=\frac{1}{focal\ length} math

**Magnification of a Lens** math M=\frac{h'}{h}=-\frac{q}{p} math math magnification=\frac{image\ height}{object\ height}=-\frac{distance\ from\ image\ to\ lens}{distance\ from\ object\ to\ lens} math

**Critical Angle** math sin \theta_c=\frac{n_r}{n_i} when n_i>n_r math math sine(critical\ angle)=\frac{index\ of\ refraction\ of\ second\ medium}{index\ of\ refraction\ of\ first\ medium} math only when index of refraction of first medium>index of refraction of second medium

Key Terms for Chapter 15  __**Refraction**__ - The bending of light as it travels from one medium to another __**Index of Refraction**__ - The ratio of the speed of light in a vacuum to its speed in a given transparent medium
 * __Lens__** - A transparent object that refracts light rays, causing them to converge or diverge to create an image
 * __Converging__** - A lense where the middle is thicker than either end.
 * __Diverging__** - A lense whose ends are thicker than the middle of the lense.
 * __Total Internal Reflection__** - The complete reflection of light at the boundary of two transparent media. This happens when the agnle of incidence is greater than the critical angle.
 * __Critical Angle__** - The minimum angle of incidence for which total internal reflection occurs
 * __Dispersion__** - The process of separating polychromatic light into its component wavelengths
 * __Chromatic Aberration__** - The focusing of different colors of light at different distances behind a lens.

15-1 Refraction


 * Refraction causes images to appear different when the object is viewed through a medium which is not air. This occurs because of the bending of light.
 * Bending light occurs when the speed of light changes due to the different medium it travels through.
 * The index of refraction for air is 1.00. Other values will be given to you accordingly.
 * The greater the index of refraction means that there will be more refraction.
 * The index of refraction is calculated based on the materials being in a vacuum.

15-2 Thin Lenses

 How to Draw a Ray Diagram:
 * = Symbol ||= Positive ||= Negative ||
 * = p ||= Object is in front of the lens ||= Object is in back of the lens ||
 * = q ||= Image is in back of the lens ||= Image is in front of the lens ||
 * = f ||= Converging Lens ||= Diverging Lens ||


 * 1) A ray that comes in parallel to the principal axis and goes out through the focal point
 * 2) A ray that comes in through the focal point and goes out parallel to the principal axis
 * 3) A ray that goes straight through the center of the lens
 * 4) The image is formed where the rays meet

Note: Ray diagrams for all situations are in the textbook on page 571

 15-3 Optical Phenomena


 * Sometimes when light goes from a higher index of refraction to a lower index of refraction, the effect total internal reflection can happen.
 * Even if there is no certaing boundary reflection can occur. Ex: Light passing from warm air to cooler air
 * Rayliegh scattering is when the atmosphere scatters the shorter wavelengths of light causing the sky to appear blue.

Practice Problems 
 * 1) An object is 30 m in front of a converging lens and the focal point is 10 m. What is the image distance?
 * 2) Find the critical angle for a water(n=1.333) to air boundary.
 * Answers:**
 * 1) 15 meters
 * 2) <span style="display: block; font-size: 130%; color: #0000ff; font-family: Arial, Helvetica, sans-serif; text-align: left;">48.6 degrees

All material on this page has been taken from Mr. Strong's class handouts and the Holt Physics Textbook Chapter 15. Practice Problem 1 was from page 575 of textbook. Practice Problem 2 was from page 581 of textbook.