Happy Tuesday! Pick up the paper from the table and get ready to take notes

Two Types of waves 1. Mechanical – needs a medium to travel through Examples: sound, water Earthquakes 2. Electromagnetic – does NOT need a medium through which to travel Ex: light waves, microwaves, x-rays, radio waves

Wave Behavior When waves interact with boundaries they can: Reflect Refract Diffract Interfere

Reflection Is when a wave bounces back off a boundary or barrier Examples: mirrors, echoes, etc.

Refraction Bending of a wave at the boundary between two different media as the wave moves from one medium to another, velocity and wavelength change, but period and frequency remain constant

Diffraction Waves moving around a barrier. Examples: sunset, mirage

Interference The superposition of waves, waves pass through each other unchanged, it is only a displacement of matter

Two types: Constructive and Destructive interference

Constructive Interference When two waves combine to produce a wave with a larger amplitude, the meet crest to crest

Destructive Interference When two waves combine to produce a wave with a smaller amplitude, they meet crest to trough

Constructive larger amplitude results in a larger amplitude Types of Interference Destructive smaller amplitude results in a smaller amplitude

Standing Waves When two waves meet with equal and opposite amplitudes Parts of a standing wave: node and antinode Node is the area of no apparent motion Antinode is the area of maximum displacement

Standing Waves A standing wave is a “resonance” Draw a standing wave. Label nodes and antinodes. Trace one complete wave on your standing wave. Node – a point where the combined wave doesn’t move Antinode – a point where the displacement is greatest, “the bump” Node

Standing waves setting up a wave standing wave formation dubstep Ruben original Rubens chanaldi board Pyro Board: Pyro boardchanaldi board Pyro board

Resonance Resonance occurs when you have a small force that is vibrating at the same frequency as another object Each new resonant wave constructively interferes with the existing wave and the amplitude builds up

Resonance resonance in a swing multiple harmonics glass 1 glass 2 time warp

A little more about Resonance Resonance: a condition that exists when the frequency of a force applied to a system matches the natural frequency of the vibration of that system tacoma bridge bridge resonance resonance examplebridge resonanceresonance example

Speed of a Wave v = velocity (m/s) f = frequency (Hertz = waves/sec) λ = wavelength (meters / wave)

IV. Speed of a Wave examples The speed of a transverse wave in a string is 15.0 m/s. If a source produces a disturbance that has a frequency of 5.00 Hz, what is its wavelength?

IV. Speed of a Wave examples A wave with a frequency of 20.0 Hz travels along a slinky. If the distance between successive compressions is m, what is the speed of the wave?

IV. Speed of a Wave examples A sound wave has a frequency of 262 Hz and a wavelength of 1.29 m. –What is the speed of the wave? –How long will it take the wave to travel the length of a football field, 91.4m? –What is the period of the wave?

Example Problem A sound wave has a frequency of 262 Hz and a wavelength of 1.29 m. a)What is the speed of the wave? b)How long will it take the wave to travel the length of a football field (91.4m)? c)What is the period of the wave?

End of day 3

Amplitude the maximum displacement of a particle of the medium from of a particle of the medium from the rest or equilibrium position

More about amplitude Amplitude is the size of the vibration, and this determines how loud a sound is. larger vibrations make a louder sound. Quieter soundLouder sound

standing wave: standing wave: a wave pattern in which two waves of the same wavelength, frequency, and amplitude travel in opposite directions and interfere

Reflection Reflection the turning back of a wave when it reaches the boundary of the medium through which it is traveling

bending obliquely different propagation speed the bending of a wave as it passes obliquely from one medium into another of different propagation speed Refraction For refraction to occur, the wave must change speed and must enter the new medium at an oblique angle.

Diffraction the spreading of a wave around a barrier or through an opening

You can view reflection, refraction, diffraction, and interference using both plane and circular waves. Click here to view a movie here clip of an actual ripple tank experiment. The ripple tank simulation found herehere can be used here to investigate wave properties.

Doppler Effect the change in frequency due to the relative motion of the wave source and the observer The observed frequency is higher when the source and observer are getting closer. The observed frequency is lower when the source and observer are getting farther away.

Click here, here,and here here to run simulations of the Doppler Effect. The Doppler Effect can be evident for all types of waves – including light, sound, water, etc…