1. Light and Sound

2. Sound Sound is a longitudinal wave Sound causes compressions and rarefactions in the air molecules Sound must travel through a material Sound can not travel through empty space Decibels – how loud the sound is Decibels are determined by amplitude (energy)

3. More Sound Remember Doppler Effect Low frequency = low pitch High frequency = high pitch Reflection, Refraction, Diffraction and Interference can all occur Sound can also be absorbed

4. Speed of Sound Sound travels at 340 m/s in air Changes speed depending on how close together the atoms in the material are The speed of sound is different in different materials – Travels fastest in solids (steel – 4512 m/s) – Travels in between in liquids (water – 1483 m/s) – Travels slowest in gases Speed also depends on the temperature – Travels faster in warm air (100⁰F – 354 m/s) – Travels slower in cold air (0⁰F – 320 m/s)

5. Supersonic Caused by motion that is faster than the speed of sound Silence as the object is approaching Loud boom after the object passes Sound is racing to catch up

6. Sonogram Sonogram or Ultrasound – sound waves used to “take pictures of something we can not see” Ocean floor, internal organs, fetus Sound waves are sent out and bounce back as they hit objects

7. What makes Light? Light is made of atoms Electrons are in energy levels(different rings) Electrons can move from ring to ring Electron moves out it gains energy Electrons move in they give off energy Energy given off = light

8. Theories of Light Particle theory – light travels as streams of particles or photons in a straight line – reflection Wave theory – light travels as waves – light travels through openings and spreads out Quantum theory – a bundle of light energy (quantum) that travels in waves

9. Particles, Waves or Quantum

10. Speed of Light Speed of light is 300,000,000 m/s Light can circle the earth 27 times in 1 second Why do we see lightening before we hear thunder?

11. Photoluminescence Glow in the dark Atoms in certain materials can store energy when they exposed to light When the light is turned off they are no longer storing energy and energy is given off as light

12. Electric Light Electricity is used to cause the electrons to jump and fall between levels Incandescence – making light with heat – light bulbs in our homes- not efficient Fluorescent – less heat more efficient

13. Polarization Light is unpolarized Unpolarized means that light travels in all directions Polarizing blocks out some of the light rays Can block horizontal or vertical waves Reduced the amount of light that reaches an object Example - sunglasses

14. Colors of Light White light is composed of all the colors of the spectrum – ROY G BIV – Light from the sun is white – what happens when it travels through a raindrop? Black light is the absence of all color – Shut yourself in the bathroom with no light – can you see any color?

15. Colors of Light Photoreceptors in the eye detect visible light The light we see is reflected light Why do we see color? – Light that hits the shirt from the sun or a light bulb is white – The color of an object depends on the light wave that is sent to our eye – A blue shirt looks blue because blue light waves are sent to our eye

16. Color in Art Do pigments mix the same way that light mixes If I mix all the colors of pigment do I paint with white paint How do I make white paint or have white paper?

17. Optics Lenses – use refraction to bend light Mirrors – reflect light Prisms – uses refraction to separate light into the colors Telescope – collection of lenses used to magnify an object Laser – one specific wavelength of light that is concentrated and organized