Waves carry energy from one place to another © 2000 Microsoft Clip Gallery WAVES Waves carry energy from one place to another

NATURE OF WAVES © 2000 Microsoft Clip Gallery Waves (Def.) – A wave is a disturbance that transfers ENERGY, but not matter.

NATURE OF WAVES Two types of waves: 1.MECHANICAL WAVES- waves that use a medium(matter) to transfer energy There are two kinds of mechanical waves:

Transverse Waves Energy causes the matter in the medium to move up and down at right angles (perpendicular) to the direction of the wave Examples: shaking a rope, water waves

Transverse Waves crest trough

Compressional Waves Energy causes the matter in the medium to move back and forth (parallel) along the same direction that the wave travels Examples: a slinky toy, sound waves

Compressional Waves compressional transverse

Compressional Waves Sound Waves are Compressional Waves Sound travel faster through solids than gases compressions rarefactions

NATURE OF WAVES Two types of Waves 2. ELECTROMAGNETIC WAVES - waves that can travel through space where there is no matter, therefore no medium is needed

Electromagnetic Waves Speed of light 300,000 km/sec 186,000 mi/sec Travel faster in gases than solids There are seven kinds of E-M waves:

Electromagnetic Spectrum © 2000 Microsoft Clip Gallery

Electromagnetic Spectrum Invisible Spectrum Radio Waves Def. – Longest wavelength & lowest frequency. Uses – Radio & T.V. broadcasting. © 2000 Microsoft Clip Gallery

Electromagnetic Spectrum Radio Waves AM – amplitude modulation Carries audio for T.V. Broadcasts Longer wavelength so can bend around hills FM – frequency modulation Carries video for T.V. Broadcasts

Electromagnetic Spectrum Invisible Spectrum (Cont.) Microwaves Are more like high frequency radio waves Causes molecules to vibrate making them hot Can cause cataracts

Electromagnetic Spectrum Invisible Spectrum (Cont.) Infrared Rays Def – Light rays with longer wavelength than visible red light. Uses: Cooking, Medicine, T.V. remote controls WE give off infrared waves!

Electromagnetic Spectrum Invisible spectrum (cont.) Ultraviolet rays. Def. – EM waves with frequencies slightly higher than visible light Uses: food processing & hospitals to kill germs’ cells Helps your body use vitamin D.

Electromagnetic Spectrum Invisible Spectrum (Cont.) X-Rays Def. - EM waves that are shorter than UV rays. Uses: Medicine – Bones absorb x-rays; soft tissue does not. Lead absorbs X-rays.

Electromagnetic Spectrum Invisible spectrum (cont.) Gamma rays Def. Highest frequency EM waves; Shortest wavelength. They come from outer space and other radioactive substances. Uses: cancer treatment.

Parts of a Wave Wavelength Distance from crest to crest OR trough to trough wavelength

Parts of a Wave Wavelength For a compressional wave: distance between the center of one compression to the center of the next compression, same with rarefactions

Parts of a Wave Amplitude (related to the wave’s energy) one-half the distance between crest and trough Rest position

Parts of a Wave Frequency The number of wavelengths that pass a given point in 1 sec. This wave’s Frequency is 4 Hz. What is this wave’s Frequency?

Parts of a Wave What is the relationship b/w frequency and wavelength? As wavelength _______, frequency ________. Therefore, long ________, means low ________.

Parts of a Wave Speed Equals the wavelength times frequency v = f

Electromagnetic Spectrum Visible Spectrum – Light we see C O L O R Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. Longest to Shortest Wavelength.

Color of Light (Cont.) Color of Objects White light is the presence of ALL the colors of the visible spectrum. White light is due to the reflection of light. Black is the result of the absorption of ALL the colors and no light is reflected back. © 2000 Microsoft Clip Gallery

Color of Light (Cont.) Primary Colors of Light Three colors that can be mixed to produce any other colored light Red + blue + green Complimentary Colors of Light Two complimentary colors combine to make white light-Magenta,Cyan,Yellow

Color of Light Transparent Objects: Translucent: Opaque: Light transmitted because of no scattering Color transmitted is color you see. The object is see-through basically Translucent: Light is scattered and transmitted some. Opaque: Light is either reflected or absorbed. Color of opaque objects is color it reflects.

How You See Retina – Rods – Cones – Lens refracts light to converge on the retina. Nerves transmit the image Rods – Nerve cells in the retina that are very sensitive to light and dark Cones – Nerve cells in the retina that help to distinguish color color

The eye

LIGHT & ITS USES Sources of Light © 2000 Microsoft Clip Gallery Sources of Light Incandescent light – light produced by heating an object until it glows. © 2000 Microsoft Clip Gallery

LIGHT & ITS USES Fluorescent Light – © 2000 Microsoft Clip Gallery Fluorescent Light – Light produced by electron bombardment of gas molecules Phosphors absorb photons that are created when mercury gas gets zapped with electrons. The phosphors glow & produce light.

LIGHT & ITS USES Neon light – neon inside glass tubes makes red light. Other gases make other colors. © 2000 Microsoft Clip Gallery

Behaviors of Light Refraction – Bending of light due to a change in speed.

Behaviors of Light

Behaviors of light Reflection – Bouncing back of light waves.

Behaviors of Light

Behaviors of Light Reflection Vocabulary Optical Axis – Base line through the center of a mirror or lens Focal Point – Point where reflected or refracted rays meet & image is formed Focal Length – Distance between center of mirror/lens and focal point

Mirrors Plane Mirrors – Perfectly flat Virtual – Image is “Not Real” because it cannot be projected Erect – Image is right side up © 2000 Microsoft Clip Gallery

Reflection & Mirrors (Cont.) Convex Mirror Curves outward Enlarges images. Use: Rear view mirrors, store security… CAUTION! Objects are closer than they appear! © 2000 Microsoft Clip Gallery

Mirrors Reflection & Mirrors (Cont.) Concave mirror Curves inward Minimizes images Use: make up mirrors, telescopes, dentist mirror, headlights

Lenses Convex Lenses Thicker in the center than edges. Lens that converges (brings together) light rays. Forms real images and virtual images depending on position of the object

Lens that is thicker at the edges and thinner in the center. Lenses © 2000 D. L. Power Concave Lenses – Lens that is thicker at the edges and thinner in the center. Diverges light rays All images are erect and reduced.

Lenses Vision – Eye is a convex lens. Nearsightedness – Concave lenses expand focal lengths Farsightedness – Convex lenses shortens the focal length.

How You See Near Sighted – Eyeball is too long and image focuses in front of the retina Far Sighted – Eyeball is too short so image is focused behind the retina. © 2000 Microsoft Clip Gallery © 2000 Microsoft Clip Gallery

Behaviors of Light Diffraction – Bending of waves around the edge of a barrier or through an opening. New waves are formed from the original. breaks images into bands of light & dark and colors. Causes the edges of shadows to be blurry

Behaviors of light Absorption- the transfer energy carried by light waves to particles of matter When you shine a flashlight, the air particles absorb some of the energy from the light

The End… © 2000 Microsoft Clip Gallery