We see the light coming from a direction determined by the law of reflection. When we see ourselves in a mirror, it appears that our image is actually behind the mirror. Here, many parallel rays are incident, but they are reflected at many different angles because the surface is rough. A mirror, on the other hand, has a smooth surface and reflects light at specific angles.įigure 16.4 Light is diffused when it reflects from a rough surface. Many objects, such as people, clothing, leaves, and walls, have rough surfaces and can be seen from many angles. Diffused light allows you to read a printed page from almost any angle because some of the rays go in different directions. Because the light is reflected from different parts of the surface at different angles, the rays go in many different directions, so the reflected light is diffused. We expect to see reflections from smooth surfaces, but Figure 16.4, illustrates how a rough surface reflects light. Light reflected in this way is referred to as specular (from the Latin word for mirror: speculum). This perpendicular line is also called the normal line, or just the normal. This concept is illustrated in Figure 16.3, which also shows how the angles are measured relative to the line perpendicular to the surface at the point where the light ray strikes it. The reflection of light is simplified when light is treated as a ray. This law governs the behavior of all waves when they interact with a smooth surface, and therefore describe the behavior of light waves as well. How does the reflected light travel from the object to your eyes? The law of reflection states: The angle of reflection, θ r θ r, equals the angle of incidence, θ i θ i. Whenever we look into a mirror or squint at sunlight glinting from a lake, we are seeing a reflection. Typically, if the surface of a transparent material is smooth, such as that of a window pane, light is transmitted partially and reflected partially. It may also be transmitted through a transparent material, such as water or glass. Light often is partially absorbed and partially reflected. Some colors of light may be absorbed and others reflected. Light can be absorbed at the surface of an opaque object. Recount and explain all the possible interactions of light with matter. Indicate that the terms right angle, perpendicular, and normal line all mean the same thing: a vertical line at a 90° angle to a flat surface. The geometry of the path of a bouncing ball is similar to that of light, but what happens at the point of impact is different at the molecular level. It is acceptable to visualize light rays as laser rays (or even science fiction depictions of ray guns).Įxplain that light bounces is a simplification. Here it means a straight line that originates from some point. It then continues in a straight line-that is, as a ray. Light may change direction when it encounters the surface of a different material (such as a mirror) or when it passes from one material to another (such as when passing from air into glass). In all these cases, light is modeled as traveling in a straight line, called a ray. Light can also arrive at an object after being reflected, such as by a mirror. Light can travel to an object through various media, such as air and glass. It can come directly from the source through empty space, such as from the Sun to Earth. There are three ways, as shown in Figure 16.2, in which light can travel from a source to another location. There are six possible ratios therefore, there are six such functions. Trigonometric functions are ratios of the lengths of two sides of a right triangle. In this chapter, we apply equations that use trigonometric functions that describe the properties of angles. In this chapter, we are focused on the first three ideas. Geometry is the study of relationships involving points, lines, angles, and shapes. The lines must be straight lines for the number to have meaning. Recall that, in geometry, angles are numbers that tell how far two straight lines are spread apart. (D) investigate behaviors of waves, including reflection, refraction, diffraction, interference, resonance, and the Doppler effect.
#REFLECTIVE LASER DIFFRACTION IMAGE MANUAL#
In addition, the High School Physics Laboratory Manual addresses content in this section in the lab titled: Mirrors and Lenses, as well as the following standards: (F) describe the role of wave characteristics and behaviors in medical and industrial applications.(E) describe and predict image formation as a consequence of reflection from a plane mirror and refraction through a thin convex lens and.(D) investigate behaviors of waves, including reflection, refraction, diffraction, interference, resonance, and the Doppler effect.The student knows the characteristics and behavior of waves. The learning objectives in this section help your students master the following standards:
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