Waves Waves as energy Waves as energy Types of waves Types of waves Parts of a wave Parts of a wave Movement of waves Movement of waves Properties of waves Properties of waves

What exactly is a wave? Definition: A wave is a rhythmic disturbance that transmits energy through matter or space Definition: A wave is a rhythmic disturbance that transmits energy through matter or space Waves move through matter but they do not move the matter itself Waves move through matter but they do not move the matter itself Ocean waves Ocean waves Sound waves Sound waves Light waves Light waves Radio waves Radio waves Microwaves Microwaves Earthquake seismic waves Earthquake seismic waves

So how are these waves different? So how are these waves different? What a wave travels through is called a medium ( ex. water, ground, air) What a wave travels through is called a medium ( ex. water, ground, air) Mechanical waves need a medium Mechanical waves need a medium Electromagnetic waves do not need a medium Electromagnetic waves do not need a medium

Types of Waves Particles in a transverse wave vibrate in an up and down motion perpendicular (right angles) to the wave direction. Particles in a transverse wave vibrate in an up and down motion perpendicular (right angles) to the wave direction. Particles in a compressional wave vibrate back and forth in the same direction that the wave travels. Particles in a compressional wave vibrate back and forth in the same direction that the wave travels. At the boundary between two media transverse and longitudinal waves can combine to form surface waves. At the boundary between two media transverse and longitudinal waves can combine to form surface waves. Longitudinal and Transverse Wave Motion Animation courtesy of Dr. Dan Russell, Kettering University

Parts of a Wave Crest: the highest point Trough: the lowest point

Compressional Waves Compression: is an area in a wave where the particles are closer together.

Compressional Waves Rarefaction is an area in a wave in which the particles are spread further apart.

Review Questions List some types of waves? List some types of waves? Name the two parts of a wave mentioned? Name the two parts of a wave mentioned? Compressional and transverse Crest and trough

Amplitude is the height of a wave and shows how much energy it is carrying. The wavelength is the distance between crests Properties of Waves Wave simulatorWave simulator courtesy of National Geographic Website

More Wave Properties Frequency is the number of waves that are produced in a given time, and measured in hertz. The wave speed is measured as distance divided by time. But it can also be calculated by multiplying wavelength by frequency. 1 23

More Review Questions Name some wave properties? Name some wave properties? Wavelength Frequency Speed Amplitude

More Wave Movement… When waves bounce off something is it called reflection. When waves bounce off something is it called reflection. A reflected sound wave is called an echo. A reflected sound wave is called an echo. When a wave is bent at an angle as it passes through a new medium it is passes through a new medium it is called refraction. called refraction. When a wave is bent around a barrier or an opening it is called diffraction an opening it is called diffraction

More Wave Properties… When the vibrations of one object cause another nearby to vibrate…that is Resonance. When the vibrations of one object cause another nearby to vibrate…that is Resonance. Some musical instruments use resonance to produce sound, like a marimba. Some musical instruments use resonance to produce sound, like a marimba.

When Waves Interfere with each other… Interference is when two waves overlap. They can overlap and make a larger wave, they can also cancel each other out. Interference is when two waves overlap. They can overlap and make a larger wave, they can also cancel each other out. Constructive interference is when they make a larger wave, Destructive interference is when they cancel each other out. Constructive interference is when they make a larger wave, Destructive interference is when they cancel each other out.

Final Review Questions What is reflection? What is reflection? –When a wave bounces off something What is refraction? What is refraction? –When a wave is bent going through different mediums What is diffraction? What is diffraction? –When a wave is bent going through an opening or around a barrier What is interference? What is interference? –When two waves overlap and either cancel out or make a larger wave