Waves

Waves

1. Mechanical waves

   • all types of sounds
   • they move through a medium, or substance
     • liquid, gas or solid

2. electromagnetic waves

   • everyday activities involve electromagnetic waves
   • they are light waves
     • depend on how spread the wave peaks are
   • they do not use a medium
     • they propagate energy forward
   • Electromagnetic wave structure
     • They transfer energy & are created by vibrating charge particles. Electric and magnetic fields create a charged particle. They vibrate prependicular to each other (90)
     • range of electromagnetic waves
       • the more energy contained in the wave, the more penetrating power they have
       • Radio waves
         • Radio waves are not sound waves. A device called a "radio" detects radio waves and converts that signal into what a speaker turns into sound.
         • Microwaves
           • A device called a "microwave" uses energy in microwaves to vibrate food molecules, heating them up.
           • Infrared waves
             • Infrared waves are commonly used in devices like remote controls to transmit a signal in the IR range.
             • Visible light waves
               • Different frequencies of visible light are detected as different colors.
               • Ultra violet waves
                 • With more energy these waves become a bit more dangerous as they can penetrate further through surfaces including our skin.
                 • X-ray waves
                   • X-rays pass through less dense objects and get absorbed by more dense objects.
                   • Gamma ray waves
                     • Gamma rays are the most penetrating due the there excessive frequency and energy. Newly developing cells are often destroyed by gamma rays.

3. Componentes of a wave

   • Peak: the peak is like the top of the hill
   • Trough: it is like the bottom of the hill
   • wave lenght: the lenght of the wave from left to right
   • amplitude: the measure of how to tall a wave is above the "center line"
   • frequency: the number of waves that pass each second (hertz)
   • equilibrum line: the center line (no motion)

4. Pulse waves

   • a single disturbance

5. Periodic waves

   • a continually oscillating motion

6. Transversal waves

   • particles are displaced prependicular to the direction of the wave travels

7. Longitudinal waves

   • the particles are displaced parallel to the direction the wave travels

8. Wave interferance

   • constructive
     • when two waves meet in such a way that their crests line up together
   • destructive
     • the crest of one wave meets the trough of another & the result is a lower amplitude

9. Formulas

   • energy wave formula
     • power transmitted by string wave = 1/2 m w2 A2 v
   • wave speed formula
     • wave speed (m/s) = frequency (Hz) x wavelenght (m)

10. wave behavior

    • Reflection: sound waves are reflected by hard flat surfaces & is why we get echoes. There is a delay between the original sound & the echo, this is why echoed sound waves have to travel twice as fast to reach our ears.
    • Transmission: When waves keep traveling in the same direction through an object.
    • Refraction: When sound and light waves pass across a boundary between two substances like air and glass, they change speed. This happens because the substances have different densities, the change in speed causes the waves to change direction.
    • Scattering: Waves depart from the expected path and spread out in multiple directions.
    • Absorption: white light can be absorbed but also reflected, when white light hits a black surface it absorbs it all and nothing is reflected. Furniture can also absorb sound.
    • Diffraction: when waves meet a gap in the barrier they pass through the gap they then spread back out after they pass through the gap. The way they spread depends on how big the gap is compared to the incoming wave lenghts.
    • standing wave: wave appearing to stand still that forms when a wave and its reflected wave interferance.