How does sound travel? Sound is a form of energy that moves in waves through matter. Sound waves are longitudinal waves or compressional waves.
Properties of Sound Waves Sound waves move out from a vibrating object in all directions. As a sound wave travels further from the object, the wave gets weaker.
How is sound produced? The movement of particles around a vibrating object creates a sound wave. Your vocal cords vibrate air molecules. They vibrate other air molecules and so on until the air molecules by the listener’s ear vibrate their ear drum.
Speed of sound The speed of sound in air at room temperature is about 344 m/s. v Sound in Air = 344 m/s
Speed of Sound If the particles are closer together, they hit faster and the wave (sound) moves faster. Does sound move faster in: air or water? water or steel?
When one particle bumps another that bumps another and so on, a sound is made. IS THERE SOUND IN SPACE?
LOUD and soft Sounds Intensity: strength of a sound Which sound is more intense, an airplane or talking? Which has more energy? Intensity is measured in Decibels. Your ear hears intensity as volume of a sound.
Intensity of a wave The intensity of a wave is shown by the amplitude. An intense sound is LOUD so it has a high amplitude. LOUDSOFT
Look at your pictures and answer the questions: Which ELECTROMAGNETIC WAVE has the most energy? The least? Which ELECTROMAGNETIC WAVE has the longest wavelength? The shortest? As frequency increases, what happens to energy? As frequency increases, what happens to wavelength? As the wavelength increases, what happens to the frequency of the waves?
Teacher Tube Video – The Electromagnetic Spectrum
How does light travel? Light is made up of bunches of energy called photons. Light travels in waves. Light is an example of a transverse wave.
Speed of light Light travels fastest through empty spaces. Light waves slow down or get stopped by matter. In air at room temperature, speed travels at: v = 300 000 km/s = 3 X 10 8 m/s Remember, sound travels at 344 m/s, so light is about 1,000,000 times faster!
Materials that light hits can be: Opaque- (Solid) Does not let light pass through. A door is opaque. Transparent- (See-through) Lets light pass through. A window is transparent. Translucent- (Not clear) Lets some light pass through. A glass of lemonade is translucent.
When light hits a material, the light may: Reflect: Bounce off Refract: Bend Get Absorbed
The Sun gives off "white" light, a mixture of all the colors in the spectrum. The object looks WHITE because an equal mixture of RED, BLUE, and GREEN light is reflected off the object and interpreted by our eyes and brain as WHITE.
You can use a FILTER to absorb a color of light.
Your TV works using little pixels that look like this: Any color can be made from a combination of these three colors of light.
The last test is the easiest to use. A person with normal color vision will see a “5” in the dot pattern. A person with Red/Green color blindness (the most common) will see a “2” revealed in the dots.
Sometimes your eyes get tired! Your rods & cones get used to what they see and it takes them some time to go back to normal.