Answer and discuss selected questions from the end of the chapter dealing with refraction and reflection. This will serve as an evaluation as well as a review

Discussion of Newton's work in showing the dispersion of white light into the various colors which comprise it. A discussion of color by reflection, using colored paper and colored filters to demonstrate. An opaque object is seen by the color of the light it reflects, all other frequencies are absorbed by the substance. White light was shown to be composed of the spectrum colors. When white light was passed through a prism, the spectrum colors were emitted, and when they were passed into a second prism, the white light was emitted. It was explained why a colored, opaque object when seen under a different color light appears black. Color by transmission was also discussed as well as the use of a pigment to absorb colors through a transparent substance

Contrast the speed of light in different media and relate it to the variation on frequency. Higher frequency light travels more slowly than lower frequency light. The working definition of dispersion was shown, and illustrated using a prism and white light. Total internal reflection was demonstrated and the critical angle defined as well as total internal reflection. Why a diamond shines brilliantly was explained by total internal reflection.

Refraction of light through a block of glass was reviewed using a print out of a beam of light passing from air through glass and back into air. The review included defining both types of rays, indicating the angles of refraction and the direction of refraction in relation to a normal drawn at the point of entry. Snell's law was given, and how the determination of the angle of refraction can be determined using the law. A concave mirror was set up, a candle image placed at a distance and the image focused on an index card. The definitions of the principal axis, the focal point, the focal length, the radius of the circle formed by the mirror, the center of the mirror, the refraction of parallel rays to the principal axis, the refraction of a ray passing through the center of the circle, the type of image formed, the size formed, and the direction of the image formed were all found from the demonstration.

Using a laser light, glass block, and ruler, the physics of refraction of light was demonstrated. A normal beam incident upon a glass block at 90 deg. was shown to pass straight through the block. The block was outlined on a sheet of white paper and the normal ray drawn from air to block to air again. The laser was incident at an acute angle to the point of entry and the passage through the block outlined on the paper.The bending of the light was obvious as the laser beam entered the glass. The bending was defined as refraction and explained to occur due to the change in speed of the ray passing from air to glass. The direction of refraction was shown to be toward the normal previously drawn. The statement that light refracts toward the normal when passing from a medium of lesser density to a medium of greater density was written. The converse was shown when light travels from a higher density to a lower density. The refraction is away from the normal. One of the classwork problems from Wed. was corrected and shown geometrically how to solve it. The bending of light was reinforced by placing a pencil leaning up in a beaker of water, and noting the virtual bending of the pencil.

The definitions and descriptions of light wave terminology was first presented. These included incident ray, normal ray, reflected ray, angle of incidence, angle of reflection, total and partial reflection, and media boundry. A demonstration using laser pointers and plane mirrors, along with a math compass, was used to measure the angles of incidence and reflection. The law of reflection was derived from the angle results, the angle of reflection equals the angle of incidence. A few problems were given at the end and reviewed. A sheet to complete for HW was given.

Review of image formed by a plane mirror. Definition of terms regarding image: upright, inverted, virtual and real. Show examples of concave and convex mirrors, and using a candle object, view the image formed by each one and describe it in terms of size, position, and ray formation. A glass block was used to show refraction of light as the laser beam passed from one medium into another. The ray was sketched on a white paper, the normal shown, the incident ray shown, and the refracted ray shown. One of the rules of refraction was derived from the direction of refraction in relation to the normal ray and the difference in media density at the surface between the 2 media.

A review sheet asking for definitions of about 12 factors dealing with light was used to start the class and review work from last week. A second sheet of problems dealing with angles of incidence and angles of reflection was was also completed at the start of the class. A set up of a plane piece glass, with a burning candle on the right side and a burning candle on the left side was used as a demonstration to determine the relationship between object distance and height and image distance and height. The object candle was moved until the image of the candle reflected from the glass overlapped exactly the burning candle on the right of the glass. The distance of the object candle was measured in cm and the image candle measured in cm. The distances from the mirror were found to be equal, as was the height of both candles and flames. When looking into a plane mirror, the image appears to be in the mirror at the same distance as the object is in front. As the object moves closer or farther away, the image moves the same distance. Di = Do. A printed ray diagram was used to show how the image is formed by a plane mirror, the rays of light were labeled as well as the distances from the mirror.

The polarization of light was presented in terms of the rays of light becoming polarized as the waves moved in only one plane. Polarizing lenses showed the effect of polarization, resulting in complete blocking of light when the lenses were at 90 degrees.

The law of reflection was demonstrated using a mirror, laser light. white paper, and a compass.
The terms incident beam, reflected beam, normal beam, angle of incidence, and angle of reflection were discussed as the lab demonstration progressed. The law of reflection was worded based on measurement.