Reflection and Refraction Pg. 57

Reflection of light Can be modeled as a light ray We can trace the path of light in ray diagrams Angle of reflection=angle of incidence i = r This equality is called the law of reflection

Calculating angle of reflection The angle of incidence and the angle of reflection are measured from a line that is perpendicular to the surface. This line is called the normal.

Measuring the angle of reflection Draw the normal by placing your protractor on the point where the light ray hits the surface. Measure the angle of incidence Draw a line equal to the angle of incidence going the opposite direction.

Mirrors Mirrors form virtual images. Curved mirrors distort images. Mirrors that bulge are called convex mirrors. Convex mirrors -make images appear smaller than they actually are. Indented mirrors are called concave mirrors. Concave mirrors magnify objects.

Colors An object’s color is the color that is reflected. The wavelength of the color is reflected into your eyes while the other colors are absorbed by the object. Mixing light of the 3 primary colors (red, green, and blue) creates white light. Secondary colors are made by mixing two primary colors. If the three primary colors are combined, all visible light is absorbed so you see black. Black is not a color, it is the absence of color.

Refraction of light Refraction makes objects appear to be in a different position The angle of refraction can be calculated The angle of refraction is also called the index of refraction

Measuring the angle of refraction Draw the normal line perpendicular to the point where the light ray hits the surface. Connect the two lines Measure the angle of incidence Measure the angle of refraction (angle between the normal and drawn line)

Measuring the angle of refraction

Lenses Lens-a transparent object that refracts light waves so they converge or diverge. Converging lens bends inward. Diverging lens bends outward. Lenses magnify objects.

Lenses for magnification Magnification is any change in the size of an image compared to the object. The focal point of a light ray is made when you can focus light rays into a small area.

The eye The eye uses refraction of light to see. Light enters the cornea. It then passes through the pupil. The light then reaches the lens where it can be curved to focus an image on the retina. The retina is composed of rods and cones. The cones are responsible for color vision.

Dispersion and prisms Prism-a transparent solid that consists of two planes that are at an angle with each other. Dispersion-when light separates into different colors because of differences in wave speed. Rainbows are caused by dispersion.