Presentation is loading. Please wait.

Presentation is loading. Please wait.

Waves. What Are Waves? Wave – a disturbance that transfers energy -- the energy transferred through a wave can be carried from the disturbance, through.

Similar presentations


Presentation on theme: "Waves. What Are Waves? Wave – a disturbance that transfers energy -- the energy transferred through a wave can be carried from the disturbance, through."— Presentation transcript:

1 Waves

2 What Are Waves? Wave – a disturbance that transfers energy -- the energy transferred through a wave can be carried from the disturbance, through the wave, to another object Ex: wind gives energy (a disturbance), creating waves on an ocean, and the ocean carries that energy to a boat, and the energy rocks the boat up and down -- the energy from the disturbance is transferred through a medium

3 Mediums Medium – the substance through which a wave travels -- in an ocean wave, water is the medium -- in sound waves, air is the medium It is important to understand that the wave DOES NOT CARRY the medium itself. It only moves energy through the medium. -- the ship doesn’t move on the waves, it only bobs up and down

4 What Causes Waves? Waves are created when a source of energy causes a vibration in a medium Vibration – a repeated back-and-forth or up-and-down motion -- some mediums can vibrate a lot with only a little energy input -- other mediums only vibrate a little with a lot of energy input -- the amount of vibration depends on the spacing and type of molecules within the medium

5 Types of Waves There are three different types of waves, which are solely characterized by the way that they move. The three types of waves are: -- Transverse waves -- Longitudinal Waves -- Surface Waves

6 Transverse Waves Transverse waves – waves whose mediums move a right angles (perpindicular) to the direction of overall wave travel -- if the wave below moves left-to-right, the medium will move up-and-down -- like whipping a rope Parts of a Transverse Wave Crest – the “high” parts of the transverse wave Trough – the “low” parts of the transverse wave

7 Longitudinal Waves Longitudinal Waves – waves whose mediums move in the same direction as overall wave travel -- like squeezing and releasing a slinky spring -- longitudinal waves are often called compressional waves Parts of a Longitudinal wave Compressions – areas where the molecules in the medium are tightly squeezed together Rarefactions – areas where the molecules in the medium are spread apart

8 Surface Waves Surface Waves – waves that form at the boundary between two different mediums -- the bouncing of waves vibrating differently create circular-shaped waves

9 Wave Properties Despite the different types of waves, all waves share the same basic properties: -- amplitude -- wavelength -- frequency -- speed When figuring out these properties on either longitudinal or transverse waves, it is necessary to remember the following: Crests on a transverse wave are equal to compressions on a longitudinal wave Troughs on a transverse wave are equal to rarefactions on a longitudinal wave

10 Amplitude Amplitude – the maximum distance the particles of a medium move from their rest position For a transverse wave: -- to find amplitude, you measure the height of the crest from the REST POSITION (or the depth of the trough) For a longitudinal wave: -- to find amplitude, you measure how strongly compressed the compressions are (or how far apart the rarefactions are spread) amplitude

11 Wavelength Wavelength – how much of the medium is between corresponding parts of a repeating wave -- wavelength is measured in meters, and is represented in formulas by the Greek letter lambda (λ) For a transverse wave: -- you find wavelength by measuring the distance between crests (or troughs) For a longitudinal wave: -- you find wavelength by measuring the distance between compressions (or rarefactions) wavelength

12 Frequency Frequency – the number of complete waves that pass a specific point in a given amount of time (usually 1 second) -- frequency is measured in a unit called Hertz (Hz), which is equal to waves/second (really is the unit per second) -- frequency is represented by the Greek letter nu ( ν ) To find the frequency of any wave, either count the number of crests or the number of compressions that pass a specific point in a given amount of time, then solve Period – the amount of time it takes for one complete wave to pass -- period is the inverse of frequency Ex: If a wave has a frequency of 3 Hz (3 waves pass per second, then its period is 1/3 second (it takes 1/3 of a second for one wave to pass)

13 Speed The speed of a wave is how much of a medium passes by a specific point in a given amount of time -- speed is in the units of meters per second (m/s) The speed of the wave is entirely determined by the medium through which the wave passes. We can calculated wave speed with the following equation: Speed = wavelength x frequency OR s = λ x ν Of course: λ = (s / ν) and ν = (s / λ)

14 Practice Problems 1.An ocean wave passes a buoy 5 times in 20 seconds. a) What is the frequency of this wave? b) What is the period of this wave? c) If the wave has a wavelength of 10 meters, what is the speed of this wave?

15 More Practice Problems 2.The speed of a rope is 40 m/s and its wavelength is 5 m. a) What is the frequency of this wave? b) What is the period of this wave? 3. A wave with a period of 0.2 seconds travels at a speed of 60 m/s. What is the wavelength of this wave?


Download ppt "Waves. What Are Waves? Wave – a disturbance that transfers energy -- the energy transferred through a wave can be carried from the disturbance, through."

Similar presentations


Ads by Google