Waves
- Characteristics of Waves
- Wave -a disturbance involving the transfer of energy from place to place
- Mechanical waves must travel through a material called a medium
- Gases like air
- Liquids like water
- Solids like rock
- Waves and Energy
- Mechanical waves form when a source of energy causes a medium to vibrate
- Vibration- repeated back and forth or up and down motion of a medium
- Types of Mechanical Waves
- Transverse waves- vibration occurs perpendicular to (at right angles to) the direction that the wave travels.
- Forms high and low points along a rope
- Crest-the top of the wave (high point)
- Trough-the bottom of the wave (low point)
- Longitudinal - vibrates the medium in the same direction that the wave travels.
- Stretching a slinky out and watching the movement go back and forth.
- Compression- the area of coils that move closer together as energy travels along the slinky
- Rarefaction- the area of coils that are spread out before or after energy travels along the slinky.
- Surface Waves- a combination of transverse and longitudinal waves.
- The energy travels at right angles causing an up and down motion and a back and forth at the same time.
- Causes particles to travel in a circular motion.
- Properties of Waves
- Amplitude
- The maximum distance a medium vibrates from its resting position. The more energy a wave has, the higher its amplitude. The height of a wave’s crest depends on its amplitude
- Transverse waves-amplitude is the maximum distance the medium moves up or down from its resting position
- Longitudinal wave- amplitude is a measure of how compressed or rarefied the medium becomes
- Very compressed=high amplitude
- Surface waves- amplitude depends on how far the water particles move above or below the surface when the water is calm
- The more energy a wave has, the higher its amplitude
- The height of a wave’s crest depends on its amplitude
- Wavelength-
- Transverse wave- wavelength =the distance from crest to crest or trough to trough
- Longitudinal wave-wavelength= the distance between compressions
- Frequency
- The number of waves that pass a given point in a certain amount of time
- Measured in hertz
- 1 wave per second 1/s = 1Hz
- 2 waves per second 2/s = 2Hz
- Speed
- How far the wave travels in a given amount of time
- ex 300 meters per second 300 m/s
- Different types of wave travel at different rates of speed
- Light is much faster than sound.
- How are they all related?
- Speed = Wavelength x Frequency
- Rule applies as long as the temperature and pressure of the medium do not change.
- Frequency = Speed/Wavelength
- Wavelength = Speed/Frequency
- Interactions of Waves
- What changes the direction of waves
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- Wave interference
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