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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