440 likes | 461 Views
Learn about compression sound waves, the human ear, light waves, electromagnetic spectrum, and the interaction of light with matter. Discover how waves work in the world of sound and light.
E N D
Ch. 4 Waves, Sound, Light • Waves • A disturbance that moves through matter or space and carries energy • Matter does not move from place to place. • Energy transfers through the matter. • Think of the wave in a stadium. • The people (matter) do not change seats, but the energy travels around the stadium.
Compression Waves • AKA: Longitudinal wave • A mechanical wave (through matter only) • Causes particles to move back and forth along the same direction in which the wave is moving.
Lesson 1 Sound Waves • Sound Waves = Compression Waves • Cannot travel through empty space. • Mechanical waves • Travel fastest through solids, then liquids, then gases. • Travel fastest in warm mediums.
Sound intensity • Amount of energy carried by the wave. • Measured by the amplitude.
Amplitude • The amount of energy that a wave carries. • Tighter compressions on a compression wave equal greater energy and louder sound.
Frequency and Pitch. • Frequency • The number of wavelengths (compressions) that pass a point each second • Pitch • The human perception of the frequency of sound. • Sounds with a low pitch have a low frequency. • Sounds with a high pitch have a high frequency.
The Human Ear • Outer Ear • Visible ear and ear canal. • Compression wave funnel • Cup your hand around your ear?
Middle Ear • Sound amplifier • Eardrum • Tiny membrane that acts like a drumhead and vibrates with the compression waves. • 3 smallest bones in the body • Hammer - Malleus • Anvil - Incus • Stirrup - Stapes
Inner ear • The sound converter • The amplified compression waves travel from the stirrup to the cochlea. • Cochlea • Fluid filled • Snail shell shaped organ lined with billions of tiny hair like structures. • convert compression waves into nerve impulses. • Nerve impulses travel through auditory nerve to brain where they are interpreted as sound. • Semi Circular Canals: Acts as device to keep a human balanced.
Sound reflection • Reverberations • Echoes • Sounds that reflect • Echolocation • Process of locating objects by bouncing sounds off of them. • Bats, Dolphins, Whales
Wave Speed • Electromagnetic waves: light waves • Travel fastest: • Space • Air (gas) • Water • Transparent solid • Mechanical Waves: compression/transverse • Travel fastest: • Solids • Water • Air • Do not travel through space
crest trough Transverse waves • A mechanical wave (Can only move through matter) • Causes particles to move back and forth at right angles to the direction of the wave motion. • Rock in a pond!
Electromagnetic Waves • Can travel through empty space, gases, liquids, and solids. • Two Transverse Waves: examples • Light waves • X rays • Wi-Fi • AM,FM radio signals • Remote controls • Contain electric transverse wave and a magnetic transverse wave
wavelength Wavelength • The distance between two like points on a wave.
1 second Frequency • The number of wavelengths that pass a point each second. • Count the crests or troughs • Count the compressions or rarefactions
2 second • Frequency equals……. • 6 wavelengths / second • 6 λ / s • 6 hertz • 6 Hz
Light Waves are….. • Able to travel up to 185,000 miles/s in empty space. • Able to travel from the sun to earth (150 million km) in 8 minutes. • Able to travel the fastest in empty space and the slowest in solids. (glass)
The electromagnetic spectrum Increasing Energy Decreasing wavelength
R O Y G B I V ROY G BIV
E.M. Waves and examples • Radio waves • AM, FM, cell signals • Microwaves • Wi-Fi, Microwave ovens, gps signals, satellite signals • Infrared waves • Heat producing bodies, remote controls • Visible Light • ROY G BIV • Ultraviolet waves • UV rays, bacteria killing lights • X-rays • Gamma Rays • Nuclear bombs, sun’s energy
Interaction of Light and Matter • Transmission • Light traveling through a material • Transparent • Almost all light travels through for a clear image • Translucent • Most light travels through, blurry image • Opaque • Light waves do not pass through • Reflection • Light bouncing off a material • Absorption • Light changing to heat
Refraction • Waves travel at different speeds depending on the properties of the material they are traveling through. • Causes the wave to change direction.
normal Law of Reflection • The angle of the incoming wave will equal the angle of the outgoing wave.
Any light? Diffraction • The bending of waves around an object. • Do shadows have crisp edges? If so, when? • Shadow of hand on desk?
Sct. 3 Mirrors, lenses, the eye • 2 major types of mirrors/lenses • Concave • The surface is curved inward
Concave lenses • One or both surfaces are curved inward • Used to spread the light waves apart
Convex • Surfaces that are curved outward
Convex lens • One or both sides are curved outward
How we see! • Light waves reflect off of an object. • Reflected light waves enter eye through cornea. • Transparent convex layer of outer eye. • Waves pass through the pupil. • Opening in the eye controlled by the iris. • Waves then pass through the lens. • Flexible convex lens that changes shape to allow you to focus on near and far objects. • Lens focuses waves on retina. • Back wall of the eye.
Retina • Contains over a hundred million light sensitive cells. • Rods • Sensitive to dim light • Help us to see in darkness. • Cones • Enable us to see colors. • 3 types • Red/yellow • Green/yellow • Blue/violet
Nearsighted vs. Farsighted. • Nearsighted • Cannot see objects far away. • Image focused to NEAR to the lens. • Farsighted • Cannot see object that are close. • Image focused to FAR from the lens.
Color in our world • The color of the objects you see represents the wavelength that reflects. white light