Waves & Vibrations Physical Science

Queen Elizabeth’s “wave” Waves are common! Examples of waves: Sound waves, visible light waves, radio waves, microwaves, water waves, sine waves, cosine waves, telephone cord waves, stadium waves, earthquake waves, waves on a string, and slinky waves Queen Elizabeth’s “wave”

Waves Anything that moves side to side, back and forth, or front to back and transfers energy from one place to another. Most common: Sound waves Ocean waves Light waves

How Waves Travel When waves travel through a solid, liquid, or gas, they are called Mechanical Waves. Common examples are SOUND waves The matter which the wave travels through is called a MEDIUM.

How Waves Travel Waves that can travel through empty space are called Electromagnetic Waves. Electromagnetic waves include all light waves, microwaves, xrays, and radio waves. Electromagnetic waves do not require a medium. (refer to reference chart)

Shapes of Waves Waves can be described using two models: Transverse Waves Longitudinal (also called compression) Waves These two labels describe the way in which the wave moves.

Types of Waves Transverse Wave Particle motion is perpendicular to direction of energy travel

Types of Waves Transverse Wave A stadium wave is an example of a transverse wave

Parts of a Transverse Wave

Orientation Transverse Wave Visible light is one type of transverse wave

Types of Waves Longitudinal Waves Particle motion is parallel to direction of energy travel

Parts of a Longitudinal Wave

Types of Longitudinal Waves Sound is one type of longitudinal wave

Types of Waves Surface waves are actually combinations of transverse and longitudinal waves Water waves are a common combination wave

Types of Waves Earthquakes are also a result of both types of waves

Other terms to know… Frequency How many waves per second Measured in Hertz (Hz)

Frequency & Wavelength The higher the frequency, the lower the wavelength. This relationship is called Non linear, Inversely Proportional.

Check your understanding! What transfers energy from one place to another? What is matter called that a wave passes through? What are the two waves a wave travels? What are the two shapes of waves? What is the relationship between frequency and wavelength?

Check your understanding! What transfers energy from one place to another? What is matter called that a wave passes through? What are the two waves a wave travels? What are the two shapes of waves? What is the relationship between frequency and wavelength? wave medium Mechanical and electromagnetic Transverse and longitudinal Non linear, Inversely Proportional

Is light a wave or a stream of particles? The debate has been going on for centuries! Light exhibits both particle-like and wave-like behavior

There are unique behaviors of waves Interference Polarization Diffraction These behaviors are dependent on BARRIERS, or anything that interrupts the travel of the wave.

What happens when two waves meet? When two waves meet in the same medium, the waves interfere. There are two possibilities Constructive Interference Destructive Interference

Types of Interference Constructive Interference Crest meets crest OR trough meets trough Results in increased AMPLITUDE

Types of Interference Destructive Interference Crest meets trough Results in decreased AMPLITUDE

Diffraction can be used to see color

Different light sources have different colors contained within them!

Standing Waves Standing waves are a result of waves that reflect back upon themselves making a pattern of constructive and destructive interference.

Polarization

Polarization Polarization is caused when light is filtered based on the direction of movement of the wave.

Check your understanding! What is anything that interrupts the pattern of a wave? What is it called when light is passed through a vertical or horizontal filter? What is it called when a wave passes through a narrow slit? What happens during destructive interference?

Check your understanding! What is anything that interrupts the pattern of a wave? What is it called when light is passed through a vertical or horizontal filter? What is it called when a wave passes through a narrow slit? What happens during destructive interference? barrier polarization diffusion a crest meets a node and they cancel each other out

How do waves interact with barriers that they can not go around? They can be REFLECTED They can be ABSORBED They can be TRANSMITTED through something called REFRACTION

Reflection Absorption Transmission

The Law of Reflection A B C D

The Law of Reflection Where is the incident wave? Where is the reflected wave? Where is the angle of incidence? Where is the angle of reflection? A D B C

Remember visible light?

Why do we see the color red?

The color red

Diffuse vs. Regular Observe the different surfaces:

Specular Reflection

Diffuse Reflection Rough Surface

What about black and white? White reflects all colors Black absorbs all colors (turns energy into heat)

What is Refraction? Refraction is when a wave changes from one medium to another. It is caused by the need to change speed in different substances.

Refraction Waves

Refraction

Total Internal Reflection Refraction Partial Reflection Total Internal Reflection!

Check for understanding! What are the three things light can do when it encounters a barrier it can not go around? What color is an object that absorbs all wavelengths of light? When a wave of light goes from air to water, it is called __________. When 100% of the light wave is reflected due to a critical angle of incidence, it is called __________________.

Check for understanding! What are the three things light can do when it encounters a barrier it can not go around? What color is an object that absorbs all wavelengths of light? When a wave of light goes from air to water and changes speed, it is called __________. When 100% of the light wave is reflected due to a critical angle of incidence, it is called __________________. Absorption, reflection, transmission black refraction Total internal reflection

Images Images are formed by transmission of light waves that replicate a barrier (any object). Two kinds: Real images are projected onto a screen Images are upside down Virtual Images are reversed right to left images are right side up

Images Images can be formed by either mirrors or lenses. Basic Shapes

Images Images can be formed by either mirrors or lenses. Concave Convex Plane

Images Creation of images is a combination of refraction and/or reflection.

Lenses

Converging Lenses Image Distance

Concave Lenses

How do you see? Light REFRACTS through lens of eye Light is ABSORBED by the rods and cones and transmitted to the brain Light REFLECTS off an object

Hearing Hearing is a result of the vibrations of the inner ear bones Humans have 3 ear bones: the stirrup, the anvil, and the hammer bones Humans can detect sound at a billionth of a centimeter displacement Humans can suffer hearing loss at about 1 billion times that threshold

Decibel Scale Source Intensity Level # Times Greater Than TOH Threshold of Hearing (TOH) 0 dB 100 Rustling Leaves 10 dB 101 Whisper 20 dB 102 Normal Conversation 60 dB 106 Busy Street Traffic 70 dB 107 Vacuum Cleaner 80 dB 108 Large Orchestra 98 dB 109.8 Walkman at Maximum Level 100 dB 1010 Front Rows of Rock Concert 110 dB 1011 Threshold of Pain 130 dB 1013 Military Jet Takeoff 140 dB 1014 Instant Perforation of Eardrum 160 dB 1016

Doppler Effect The Doppler effect is when the sound source is moving Examples include a blaring horn, sirens Incoming sound waves are usually louder & higher frequency Outgoing waves (after the car has passed), are lower frequency and softer

Doppler Effect

Sonic Boom When an airplane travels fast enough to exceed the speed of sound, it produces a sonic boom A sonic boom is the result of the “piling up” of compression waves This creates a high pressure area that is followed by a bunch of rarefactions (low pressure) and the BOOM!