PASS Content Standard 3.2 Waves, including sound and seismic waves, waves on water, and light waves, have energy and can transfer energy when they interact with matter (such as used in telescopes, solar power, and telecommunication technology.

Nature of waves - 2 min

The motion of the medium is at right angles to the direction the wave is moving. Particles of the medium move up and down, but not horizontally.

The motion of the medium is parallel to the direction the wave is moving. Particles of the medium move horizontally, but not up and down.

Baseline The “top” of the wave.

Baseline The “bottom” of the wave.

Baseline The distance between the same points on two successive waves.

Baseline The maximum displacement of particles from the baseline.

The number of complete waves per unit of time

Units of frequency are Hertz (Hz) 1 Hz = 1 wave per second

Wave Speed speed = wavelength X frequency

Wave Interactions - 7 min

The bouncing back of a wave after striking a boundary.

The bending of a wave due to a change in speed.

The bending of a wave around the edge of a barrier.

The interaction of two or more waves to produce a single new wave.

Constructive interference - crests of two waves combine

Destructive interference - a crest combines with a trough

Sound Waves - 3 min

The speed of sound depends on the type of medium and the temperature of the medium.

Speed of Sound - 3 min

The speed of sound depends on the temperature and nature of the medium. solidliquid gas

The speed of sound in air: m/sec at 0 o C 340 m/sec at 15 o C 346 m/sec at 25 o C The speed of sound in water is 1500 m/sec The speed of sound in steel is 5200 m/sec

A change in the frequency and pitch of a sound due to the motion of either the sound source or observer.

The speed of sound in air is 340m/s

The amount of energy in a wave. Amplitude determines the intensity of a wave.

Sounds over 120 decibels will cause pain in the ears. Ear damage can begin as low as 85 decibels.

Pitch is how low or high a sound is. Frequency determines the pitch of a sound. Humans can hear sounds ranging from 20 Hz to 20,000 Hz.

Thunder has a low pitch with a frequency less the 50 Hz. A basketball whistle has a high pitch with a frequency close to 1000 Hz.

Timbre is the "quality" of sound. An object producing sound is actually vibrating at several frequencies. The better these pitches blend, the better the sound quality.

Sound with a pleasing quality, a definite identifiable pitch, and a definite repeated rhythm. Crumping

Sound with a no pleasing quality, no identifiable pitch, and no definite repeated rhythm.

The Human Ear

The Ears and Hearing - 6 min

The Outer Ear: Ear flap - Catches sound waves and turns them into the ear canal. Ear canal - Funnels the waves to the eardrum. Eardrum - A tightly stretched membrane that vibrates as the sound waves strike it.

Ear Flap Ear Canal Eardrum Outer Ear

The Middle Ear: Hammer - Bone touching the inside of the eardrum. Anvil - Bone that picks up vibrations of the hammer and passes them to the stirrup. Stirrup - Bone touching the membrane leading to the inner ear.

Hammer Anvil Stirrup Middle Ear

The Inner Ear: Cochlea - A coiled, fluid-filled cavity. This cavity contains hundreds of fibers that are attached to nerves leading to the brain. The motion of the fluid causes the fibers to send impulses to the brain, where they are interpreted as sound.

Cochlea Inner Ear

Light - 3 min

1. The atoms is normal. 2. An electron absorbs a packet of energy. 3. The electron jumps to a higher energy level.

4. The atom is now "excited". 5. The electron drops back to its normal energy level. 6. The electron releases the excess energy as a photon of LIGHT.

Using the Electromagnetic Spectrum - 3 min

Transparent - Light passes through so you can see clearly. Translucent - Light passes through but is scattered so you cannot see clearly.

Opaque - Light does not pass through an object.

A comparison of the speed of light in air with the speed of light in a certain material. The larger the index of refraction, the more light rays are bent.

An object that forms a spectrum as light passes through it.

Incandescent Light Electricity passes through a wire filament making it glow.

Fluorescent Light Electricity causes phosphors inside a glass tube to glow.

Neon Light Electricity excites the atoms of a gas to produce photons of light.

Polarized Light Light with all waves vibrating in the same plane.

Laser Light Coherent light of only one frequency. Coherent light is in phase, meaning the crests and troughs of the waves all move in the same direction at the same time.

LightPigments

The science of controlling light.

Light can be controlled in 3 ways: Block it, Bend it, or Reflect it

Plane Mirror - A flat surface that reflects light and forms a virtual image. Plane mirrors produce virtual images. A virtual image is one that appears behind the surface of the mirror. Concave Mirror - The surface of the mirror curves inward. Concave mirrors produce real images. A real image is one that can be projected onto a screen. Convex Mirror - The surface of the mirror curves outward.

Mirrors - 3 min

Convex Lens - Thicker in the center than at the edges. The point at which the rays come together is called the focal point. When the rays continue past the focal point, an inverted, real image forms. Concave Lens - Thicker at the edges than at the center. When parallel rays pass through a concave lens, they are bent away from the center.

Double Convex Lens

Double Concave Lens

Lenses - 3 min

Ideally, the image formed by the eye's lens should fall directly on the retina.

Nearsightedness The eyeball is too thick, causing the image to focus in front of the retina. A person can't see distant objects, but can see near objects well.

Nearsightedness A concave lens can be used to correct this problem.

Farsightedness The eyeball is too thin, causing the image to focus behind the retina. A person can see distant objects clearly, but has difficulty with near objects.

Farsightedness A convex lens can be used to correct this problem.

The number of frames per second at which sequential images are no longer seen separately.

Humans can distinguish from 16 to 24 frames per second.

Motion pictures show about 30 still frames per second.