Light and Its Uses
Reflection of Light• specular (regular) reflection– all light rays that hit a smooth surface are
reflected at the same angle
• diffuse reflection– reflected light is scattered in many directions
due to a rough surface
Mirrors
• Plane (flat) mirrors
– flat surface
– left and right are reversed
– give a virtual image
• the image you see is where you think the light came from, not where it actually came from
• concave mirrors
–mirror curves inward
– help to concentrate light on a spot called the focal point
• convex mirrors– mirror surface curves outward– the focal point is behind the mirror– used in automobile rear-view mirrors– objects appear farther than they really are
concave mirror
convex mirror
Color• the color of an object is determined what
color(s) of light are reflected– example: a red object looks red because red
light is reflected
Refraction of Light
• white light is made up of all the visible colors (ROYGBIV)
• each color (wavelength) of light is refracted (bent) a different amount– prisms can separate white light into its colors
(called dispersion)– red, with the longest wavelength, bends the
least– violet, with the shortest wavelength, bends the
most
• may make objects appear to be in different positions
A Rainbow
Lenses• transparent material that bends light to
create an image– converging lens• magnifying glass
– diverging lens• viewfinders in cameras
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