MT 5 LT 2 – Behavior Of Waves

Let’s Review LT 1 – Basic Properties of Transverse Waves Amplitude Wavelength Frequency Speed DO NOT COPY

Amplitude Amplitude is the distance from the rest to crest or rest to trough. Farther medium moves as it vibrates, larger the amplitude. Greater the amplitude, greater the amount of energy DO NOT COPY

Wavelength Wave travels certain distance before it starts to repeat. Distance between 2 corresponding parts of a wave. Transverse measure from crest to crest or trough to trough. DO NOT COPY

Properties of Longitudinal/Compressional Waves DO NOT COPY

Longitudinal Wave The motion of the medium vibrates in the same direction (parallel) as the wave travels. Example: Slinky DO NOT COPY

Longitudinal Wave Compressions: The parts where the coils are close together Rarefactions the parts where the coils are spread out DO NOT COPY

Amplitude of a longitudinal wave. The amplitude of a longitudinal wave is a measure of how compressed or rarefied the medium becomes. DO NOT COPY

Wavelength Distance between 2 corresponding parts of a wave. Longitudinal measure from one compression to the next. DO NOT COPY

HOW DO WAVES INTERACT? LT 2 - Wave Behaviors

WHAT HAPPENS WHEN… Wave Behaviors A WAVE MEETS A HARD SURFACE LIKE A WALL? A WAVE ENTERS A NEW MEDIUM? A WAVE MOVES AROUND AN OBSTACLE? A WAVE MEETS ANOTHER WAVE?

HOW DO WAVES INTERACT? Wave Behaviors

Ways Waves Interact Reflection Refraction Diffraction Interference Constructive Destructive Doppler Effect Polarization

Reflection pg 508 What happens when a wave hits a wall or some other fixed object? To find out, tie a rope to the back of a chair. Gently shake the rope up and down once to send a single pulse along the rope as shown. Observe what happens when the pulse hits the chair.

Reflection Video: Click HereClick Here Definition: If reflection occurs at a fixed boundary, the reflected wave will be upside down compared to the original wave. This happens because the wave hits a fixed barrier and bounces off of it

Reflection Important: In Reflection wave hits a FIXED barrier and cannot pass Real Life: Basketball off backboard Related Items: mirror Frequency, angle Fixed boundary=flipped reflection Sound would echo

Refraction pg 509 Video: Click HereClick Here Definition: All waves change speed when they enter a new medium. Bending occurs when one side of the wave enters the new medium before the other side.

Refraction Ex: Pencil: half in water, half in air and it looks bent

Refraction Important: Wave must enter NEW medium at an angle-wave changes speed Real Life: Hard to spear a fish Related Items: Wavelengths travel at different speeds in different substances medium-air vs water wave speed

Reflection v Refraction Reflection’s barrier is not moving, it is fixed as wave hits it (The wave can’t pass through it) Refraction: wave bends as it continues into a new medium; speed also changes.

Diffraction pg 510 Video: Click HereClick Here Definition: When a wave passes a barrier or moves through a hole in a barrier it bends and spreads out.

Diffraction Important: Wavelength determines diffraction as well as gap size. Long wavelength=long diffraction: bends and spreads out a lot Short wavelength=short diffraction: slightly bends Real Life Connection: Waves that travel around a log or move through a gap Related Items: Wave speed Bend barrier

Interference – Constructive & Destructive Video: Click HereClick Here

Constructive Interference pg 511 Definition: Constructive interference occurs whenever two waves combine to make a wave with a larger amplitude.

Constructive Interference Important: Constructive waves build on each other Real life Connection: Rouge waves Related Items: Amplitude increases Bigger wave

Destructive Interference pg 511 Definition: Destructive interference when the amplitudes of two waves combine producing a smaller amplitude.

Destructive Interference Important: Destructive waves can cancel each other Real life Connection: Muffler on a car Related Items: Amplitude decreases smaller wave

Doppler Effect pg 516 Video: Click HereClick Here Definition: Change in pitch of a sound source due to the relative motion of the source and the observer. Observed when a police car, w/sirens blaring, passes you, traveling in the opposite direction, at a high speed.

Doppler Effect It is about pitch, NOT loudness. As something gets closer, it has a higher pitch As it passes you, the pitch gets lower

Doppler Effect Important: Long Wavelength creates a low frequency/pitch – after car passes you Small Wavelength creates a high frequency/pitch – as car approaches you Real Life: Can’t hear oncoming cars Related Items: Faster the object moves, the closer in front and farther in back the waves get

Polarization pg Video: Click HereClick Here Definition: (ONLY with Transverse waves) Transverse waves can travel in all directions. If it is linearly polarized (made to go through a filter), then the transverse vibrations in the wave are all in the same direction. Light is frequently used as an example of polarization.

Polarization Important: Unpolarized light – vibrates in all directions Polarized light – vibrates in one direction Real Life: Polarized Sunglasses Related Items: Plane-flat surface Light waves that travel in all directions

You should have…. a.If reflection occurs at a fixed boundary, the reflected wave will be upside down compared to the original wave. b.Refraction occurs when a wave enters a new medium at an angle because one side of a wave front moves more slowly than the other side. c.The larger the wavelength is compared to the size of an opening or obstacle, the more a wave diffracts. d.The types of interference are constructive and destructive interference.

Take a few minutes and fill this out…..

Polarization Important: Unpolarized light vibrates in all directions. Polarized light has been filtered and only vibrates in one plane Real Life: Sunglasses Related Items: Plane-flat surface Light waves-all directions