Waves

Wave EnergyWave-any disturbance that transfers energy

from one place to another without transferring matter

transfer energy AWAY from the source of the energy

Medium – material through which wave energy is transferredwaves travel fastest through solids because

molecules are closer together

Mechanical WavesMechanical Waves – a wave that can travel

only through matter. (They need a medium-(solid, liquids, or gasses)

Types of Mechanical Waves:Sound Waves- (longitudinal waves)Water Waves- (orbital waves)Seismic Waves-( longitudinal and transverse)

Mechanical Waves - TransverseTransverse Waves:

the disturbance is perpendicular to the direction the wave travels

move in an up-and-down motiontop of the wave is called the crest and the base

of the wave is called the trough

Mechanical Waves - LongitudinalLongitudinal Waves

the disturbance moves parallel to the direction the wave travels

move in a back-and-forth motionwhere particles are crowded together is called

the compression, where they are farther apart is called the rarefaction

Mechanical Waves – OrbitalOrbital Waves-(Surface waves)

combination of a transverse wave and a longitudinal wave

ocean waves are an example of surface waves the water moves up and down while the wave

energy moves forward objects in an ocean wave bob up and down in a

circular motion

WRITING RESPONSEWhat do waves transfer from place to place?

What kind of materials can mechanical waves move through?

Electromagnetic (EM) WavesElectromagnetic Waves (EM) – can travel

through empty space and through matter; does NOT need a medium

All electromagnetic waves are transverseex. light waves, x-rays, ultraviolet waves, microwaves,

radio wavesThe type of EM waves given off by an object

depends mainly on the temperature of the object Ex: humans give off infrared rays

PROPERTIES OF WAVES

Amplitude – the height of a wave, from resting position to crestthe larger the amplitude, the more energy the

wave has

Wavelength – distance from any point on a wave to an identical point on the next wavethe shorter the wavelength, the more energy

the wave has

shorter wavelength = more energy

higher amplitude = more energy

Frequency – the number of waves produced in a given amount of time; measured in hertz (Hz)1 Hz = 1 wave per secondfrequency and wavelength are inversely

related, which means as one decreases the other increases (and vice versa)

Wave Speed – the speed at which a wave travelsto calculate: wave speed (s) = frequency (f) x

wavelength (λ)s = f x λ

higher frequency = shorter wavelength = more energy

Wave Speed Calculations1) Determine the wave speed of a wave that

has a wavelength of 5 m and a frequency of 4 Hz.

s = f x λ = 4 Hz x 5m = 20 m/s

2) What is the speed of a wave that has a wavelength of 2 m and a frequency of 6 Hz?

3) What is the frequency of a wave if the wave has a speed of 12 cm/s and a wavelength of 3 cm?

Wave Speed Calculations2) What is the speed of a wave that has a wavelength of 2 m and a frequency of 6 Hz?

s = f x λ s= 6 Hz x 2m s= 12 m/s

3) What is the frequency of a wave if the wave has a speed of 12 cm/s and a wavelength of 3 cm? s = f x λ 12 cm/s= f x 3cm f= 4 Hz

WRITING RESPONSEWhen comparing a category 3 hurricane and

a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why?

WRITING RESPONSEWhen comparing a category 3 hurricane and

a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why?

A category 5 hurricane will create water waves with the most amplitude because it carries

more energy

WAVE INTERACTIONS

Wave InteractionsAbsorption – the transfer of energy by a wave

to the medium through which it travelsex. air absorbs sound, dark objects absorb light

Transmission – the passage of light through an object, like a window

Reflection – the bouncing of a wave off a surface

ex. sound wave reflection is called an echoNormal – line perpendicular to the surfaceAngle of Incidence – angle between the incoming

wave and the normal

Law of Reflection - when a wave is reflected from a surface, the angle of the reflection is equal to the angle of incidence

Wave InteractionsRefraction – the change in direction of a wave

that occurs as the wave changes speed when moving from one medium to anotherex. light waves are refracted when they pass

from air to rain drops, and a rainbow is formed

Wave InteractionsDiffraction – the change in direction of a wave

when it travels by the edge of an object or through an openingex. music around a corner

Wave InteractionsInterference – occurs when waves that

overlap combine, forming a new waveConstructive Interference – when two crests or

two troughs combine, therefore combining the energy, and making a larger crest or trough

Destructive Interference – when the crest of one wave meets the trough of another wave, resulting in no wave at all

Standing Wave – two waves of the same wavelength overlap and the wave seems to be standing still

WRITNG RESPONSEHow do waves change as they pass from one medium to another?

Compare and contrast reflection, refraction, and diffraction.

WRITNG RESPONSEHow do waves change as they pass from one medium to another?Waves bend or change direction because their speed changes as they pass through one medium to another

Compare and contrast reflection, refraction, and diffraction.Reflection, refraction, and diffraction are all ways waves interact with matter. Reflection occurs when a wave strikes a surface and bounces off. Refraction occurs when a wave changes direction as it passes from one medium to another. Diffraction occurs when waves change direction as they pass by the edge of an object or through an opening.