light

LIGHT

Objectives:The student will investigate and understand basic characteristics of white light. Key concepts include:

• The visible spectrum, light waves, reflection, refraction, diffraction, opaque, transparent, translucent;• Optical tools (eyeglasses, lenses, flashlight, camera, kaleidoscope, binoculars, microscope light boxes, telescope, prism, spectroscope, mirrors); and• Historical contributions in light

Explain the relationships between wavelength and the color of light. Name the colors of the visible spectrum.

Vocabulary:• Waves: a disturbance which carries energy and

that travels away from the starting point.• Wavelength: the distance between one crest of a

wave and the next crest (distance between compressions); red is longest and violet is shortest

• Peak: the highest point of a light wave• Trough: the lowest point of a light wave• Frequency: the number of waves (light or sound)

produced in a given unit of time, such as a second

• Visible spectrum (visible light): a combination of several different wavelengths of light traveling together. It is part of the Electromagnetic Spectrum.

• Reflection: the bouncing of light from a surface• Refraction: the bending of light as it passes through one material to another

Diagram Representation of Light Wave

Reflection Refraction

A convex lens causes light to converge, or focus,producing an image that is smaller than the original object.

Two kinds of Lens

A concave lens causes light to diverge, or spread out,producing a larger image than the original.

Optical Tools that has lenses, mirrors and/or prisms in it:

• eyeglasses• flashlights • cameras • binoculars• microscopes

Eyeglasses: have lenses

Flashlight: has lenses and a mirror

Cameras: have lenses, mirrors, and a prism

Binoculars: have lenses and prisms

Microscope: has lenses

Plastic wrap Wax paper Aluminum Foil

Transparent Translucent Opaque

Three kinds of Materials:

Transparent: materials that allow all light to pass through Translucent: letting light through but scattering it Opaque: materials that do not let light throughTransmit: to send (as in sound or light). It also means light passing through an object

Scientist with contributions in using and creating optical tools:

Galileo Galilei

• Italian• Lived from 1564-1642• Developed the refracting telescope• Developed the first known example of the

microscope

Robert Hooke

• English• Lived from 1635-1703• Devised the compound microscope and

illumination system• Discovered plant cells• Examined fossils with a microscope

Anton van Leeuwenhoek

• Dutch; born in Holland• Lived 1632-1723• Made over 500 simple microscopes• Discovered bacteria, free-living and

parasitic microscopic protists

Isaac Newton

• English• Lived from 1643-1727• Discovered that white light was not a

simple entity, but splits into a range of colors

• When he passed white light through a glass prism, he noted that a spectrum of light was formed; particle theory of light

• Reflecting telescope