Wave Properties

Waves In General: Waves are energy traveling through a “medium” (solid, liquid or gas material) Waves are energy traveling through a “medium” (solid, liquid or gas material) Properties of waves depend on elasticity of the medium: Properties of waves depend on elasticity of the medium: Sound speeds in different mediums Air (0 degrees) 331 m/s Air (20 degrees) 343 m/s Water 1500 m/s Iron 4400 m/s Glass 5100 m/s As you can see, sound travels at different speeds depending on the medium Think: Why would waves move through solids faster than a gas like “air”?

Sound Travel in “Space”: So if the astronauts communications device fails, can they take their helmets off (don’t worry about the whole “breathing” thing here) and just talk? Think: What is missing for the energy of sound to travel between them? If there isn’t enough atoms (“air”) out there, can the sound energy actual travel anywhere? So can there be any sounds out there at all?

Properties of Waves: They may not look like much, but waves have several features that we use to describe what result the energy will have:

Wavelength: Wavelength: The distance between any point on a wave and the equivalent point on the next phase. Literally, the length of the wave. It is either the distance between two different tops of waves Or the distance between two different bottoms of waves, either way, it will be the same!

Wavelength: Wavelength: The distance between any point on a wave and the equivalent point on the next phase. Literally, the length of the wave.

Amplitude: Amplitude: The strength or power of a wave signal. The "height" of a wave when viewed as a graph. The Amplitude is the height of a wave from bottom to top

Amplitude Amplitude: The strength or power of a wave signal. The "height" of a wave when viewed as a graph. (Also note that high amplitude = high energy.) If I wanted to increase the amplitude, I simply increase its height. A shape

Amplitude Amplitude = Loudness = Volume Higher amplitudes are interpreted as a higher volume, hence the name "amplifier" for a device which increases amplitude.

Amplitude = Loudness How we sense Amplitude = Loudness Higher amplitudes are interpreted as a higher volume, hence the name "amplifier" (or “amp’s”) for a device which increases amplitude. More Amplitude means more height! Less Amplitude means less height! Think: Which wave will have a louder sound?

1 secondFrequency: Frequency: The number of times the wavelength occurs in one second. (Like waves per second) The faster the sound source vibrates, the faster the wave and the “higher” the frequency. Low High

How we sense Frequency = “Pitch” Higher frequencies are interpreted by our brain as a higher pitch. For example; when you sing in a high-pitched voice you are forcing your vocal chords to vibrate quickly. (Also note that high frequency = high energy.) Our ears are sensitive to sound energy. We perceive a high frequency as a high pitched note; a low frequency as a low pitched note. How Frequency Affects Sound: “High” note = High Frequency “Low” note = Low Frequency Notice: Did the Amplitude change when we changed the frequency?

“Light” Spectrum: A graph that shows the different frequencies of light waves and the resulting types of light and colors. Radio | Micro | Infra Red | Visible Light | UV | X-Ray | Gamma Light Frequency = Type of light and color Higher frequencies are interpreted as different types light. For example; a higher frequency can make a darker color. Notice that low Frequencies make radio, micro, and Infrared waves of energy Higher Frequencies make Ultraviolet, X ray, and Gamma waves of energy Also different Frequencies make colors. This is the only type of light Humans can see. Lastly: Notice that all These Waves have the same amplitude!

So what is White Light? White Light is actually made up of many different colors – each color is made up of its own frequency and wavelength. When you combine the colors together it actually makes white light! You can shine white light into a prism and it separates it out into the mix of colors

Notice the white light coming in Notice the split spectrum coming out.

Wave Speed: Average Wave Speeds: can vary depending on the type of energy Light = 3.0x108 m/s Sound ≈ 340 m/s (Faster than most jets) Of course it still depends on what medium the Energy is travelling through!!!

Why we see the firework first – then hear it after? Light travels faster than Sound!!!

Hammering It takes longer for the sound energy To reach your ear than for the light Energy to reach your eye! That’s why we can see something before we can hear it!

If waves propagated in only 2D like waves on a pond, then if we moved the candle up a little higher we wouldn’t be able to see it. Wave hitting my eye – I can see it! If the Wave propagated out on a separate 2D plane, I wouldn’t see it.

Since waves propagate in 3D, we can see the light from this candle in all directions. Same thing applies with sound.

Wave motion is like an onion: Spreads out in all directions equally! Intensity: The further out you go from the energy source, the less intense the wave is. The reason the farther out planets are “colder” is because they are farther from the source of the heat and light in our solar system. EX: If you wanted to save your ears from the loudness of the speakers – scoot back! Think about it; is there any direction (up down, left, right…etc…) that the sun DOESN’T shine it’s light and heat energy? that the sun DOESN’T shine it’s light and heat energy?

Movement of Waves: The layers of an onion, are a good representation of how waves look as they travel In every direction equally at the same time! The exception is “surface waves” (like wind generated ocean waves). They only travel on a “surface” (not up and down). HEY! I’ve got layers too!!!

Common Instruments we use to sense light energy in our lives Telescope MRI Machine Satellite Dish Glasses

Common Instruments we use to sense light energy in our lives Sonar Microphone Hearing Aid Stethoscope Ultrasound