 # Waves.

## Presentation on theme: "Waves."— Presentation transcript:

Waves

Wave Energy Wave-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 transferred waves travel fastest through solids because molecules are closer together

Mechanical Waves Mechanical 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 - Transverse
Transverse Waves: the disturbance is perpendicular to the direction the wave travels move in an up-and-down motion top of the wave is called the crest and the base of the wave is called the trough

Mechanical Waves - Longitudinal
Longitudinal Waves the disturbance moves parallel to the direction the wave travels move in a back-and-forth motion where particles are crowded together is called the compression, where they are farther apart is called the rarefaction

Mechanical Waves – Orbital
Orbital 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 RESPONSE What do waves transfer from place to place? What kind of materials can mechanical waves move through?

Electromagnetic (EM) Waves
Electromagnetic Waves (EM) – can travel through empty space and through matter; does NOT need a medium All electromagnetic waves are transverse ex. light waves, x-rays, ultraviolet waves, microwaves, radio waves The 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 crest
the larger the amplitude, the more energy the wave has Wavelength – distance from any point on a wave to an identical point on the next wave the shorter the wavelength, the more energy the wave has

shorter wavelength = more energy
higher amplitude = more energy

Wave Speed – the speed at which a wave travels
Frequency – the number of waves produced in a given amount of time; measured in hertz (Hz) 1 Hz = 1 wave per second frequency and wavelength are inversely related, which means as one decreases the other increases (and vice versa) Wave Speed – the speed at which a wave travels to calculate: wave speed (s) = frequency (f) x wavelength (λ) s = f x λ

higher frequency = shorter wavelength = more energy

Wave Speed Calculations
1) 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 Calculations
2) 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? 12 cm/s= f x 3cm f= 4 Hz

WRITING RESPONSE When comparing a category 3 hurricane and a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why?

WRITING RESPONSE When 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 Interactions Absorption – the transfer of energy by a wave to the medium through which it travels ex. 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 echo Normal – line perpendicular to the surface Angle 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 Interactions Refraction – the change in direction of a wave that occurs as the wave changes speed when moving from one medium to another ex. light waves are refracted when they pass from air to rain drops, and a rainbow is formed

Wave Interactions Diffraction – the change in direction of a wave when it travels by the edge of an object or through an opening ex. music around a corner

Wave Interactions Interference – occurs when waves that overlap combine, forming a new wave Constructive 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 RESPONSE How do waves change as they pass from one medium to another? Compare and contrast reflection, refraction, and diffraction.

WRITNG RESPONSE How 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.