waves: light moving waves carry energy from one place to another
TRANSCRIPT
WAVES: LIGHT moving
Waves carry energy from
one place to another
The NATURE of WAVES
Waves – A wave is a disturbance that transfers energy.
A medium – A substance which transmits a wave.
Speed of waves – depends on the properties of the medium.
This drawing shows
1. reflected energy 2. transmitted energy 3. emitted energy 4. absorbed energy
This drawing shows
1. reflected energy 2. transmitted energy 3. emitted energy 4. absorbed energy
This drawing shows
1. reflected energy 2. transmitted energy 3. emitted energy 4. absorbed energy
This drawing shows
1. reflected energy 2. transmitted energy 3. emitted energy 4. absorbed energy
Light & the Electromagnetic Spectrum
LIGHT: What Is It?
Light Energy Atoms
As atoms absorb energy, electrons jump out to a higher energy level.
Electrons release light when falling down to the lower energy level.
Photons - bundles/packets of energy released when the electrons fall.
Light: a stream of Photons
Electromagnetic Waves
Speed in Vacuum300,000 km/sec186,000 mi/sec
Speed in Other MaterialsLight is slower in Air, Water, Glass
Transverse Waves
Energy is perpendicular to direction of motion
Moving photon creates electric & magnetic fieldLight has BOTH Electric & Magnetic
fields at right angles!
Electromagnetic Spectrum
Electromagnetic Spectrum
Radio WavesLongest wavelength & lowest frequency.
Size of a football field +Radio & T.V. broadcasting.
Electromagnetic Spectrum
Microwaves About the size of a
baseball Used in radar,
cooking, pagers, cells
Electromagnetic Spectrum
Infrared Rays Light rays with longer wavelength than red light.
Longer IR is heat Cooking, Medicine, T.V. remote controls
Which is the same thing as heat?
1. Visible light 2. Infrared light 3. Radio waves 4. Ultraviolet radiation
This drawing shows
1. convection 2. transmitted energy 3. conduction 4. absorbed energy
This drawing shows
1. convection 2. transmitted energy 3. conduction 4. absorbed energy
LandSat satellite
Electromagnetic Spectrum
Visible Spectrum – Light we can seeRoy G. Biv – Acronym for Red,
Orange, Yellow, Green, Blue, Indigo,
& Violet.Largest to Smallest Wavelength.
Electromagnetic Spectrum
Ultraviolet rays.EM waves slightly shorter than visible light
Used in food processing & hospitals to kill germs’ cells
Helps your body use vitamin D.
Electromagnetic Spectrum
X-Rays are shorter than UV rays. Medicine – Bones absorb x-rays; soft tissue does not.
Lead absorbs X-rays.
Electromagnetic Spectrum
Gamma rays Shortest wavelength EM waves. They come from outer space. Uses: cancer treatment.
The Atmosphere absorbs wavelengths
LIGHT: Particles or Waves?
Wave Model of LightExplains most properties of light
Particle Theory of LightPhotoelectric Effect – Photons of
light produce free electrons
LIGHT: Refraction of Light
Refraction – Bending of light due to a change in speed. Index of Refraction – Amount by which a
material refracts light. Prism – Glass that bends light. Different
frequencies are bent different amounts & light is broken out into different colors.
Refraction
LIGHT & Reflection
Reflection – Bouncing back of light wavesRegular reflection – mirrors smooth
surfaces scatter light very little. Images are clear & exact.
Diffuse reflection – reflected light is scattered due to an irregular surface.
Color of Light
Color of Objects White light is the presence of ALL
the colors of the visible spectrum. Black objects absorb ALL the colors
and no light is reflected back.
How You See
Retina – Lens refracts light to converge on the
retina. Nerves transmit the image Rods –
Nerve cells in the retina. Very sensitive to light & dark
Cones – Nerve cells help to see light/color
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
LIGHT & USES: LASERS
LASERSAcronym: Light Amplification by
Stimulated Emission of RadiationCoherent Light – Waves are in
phase so it is VERY powerful & VERY intense.
Summary
Waves carry energy from one place to another
The Electromagnetic Spectrum is an arrangement of 7 kinds of radiation, based on their wavelength
Each kind of radiation has different wavelengths
Each color of light has different wavelengths
Summary
Radio waves, microwaves, infrared rays, light, ultraviolet light, x-rays and gamma rays are different wavelength bands in the spectrum of electromagnetic waves
The speed of EM radiation in vacuum is approximately 186,000 miles/sec
The End…
© 2000 Microsoft Clip Gallery