Bell Ringer 1.How would you describe a wave to someone who had never seen one before? 2.List 3 different types of waves.

Intro to Waves Physical Science

Agenda Guided Notes: Introduction to Waves Guided Notes: Introduction to Waves Parts of a Wave Parts of a Wave Transverse & Longitudinal Transverse & Longitudinal Boundary Interactions Boundary Interactions Constructive & Destructive Interference Constructive & Destructive Interference

What is a Wave? A wave is a disturbance that carries energy from one place to another. A wave is a disturbance that carries energy from one place to another. A medium is the substance that the wave travels through. A medium is the substance that the wave travels through. Example 1: When there are waves on the ocean the medium is water. Example 1: When there are waves on the ocean the medium is water. Example 2: When sound travels across the room the medium is air. Example 2: When sound travels across the room the medium is air.

WATER is the MEDIUM AIR is the MEDIUM

Parts of a Wave There 3 ways that waves can be measured: There 3 ways that waves can be measured: 1.Wavelength: How far apart the waves are. 2.Amplitude: How tall the wave is. 3.Frequency: How many waves pass by in a period of time.

Amplitude Crest Wavelength Resting Position TroughAmplitude

Transverse and Longitudinal Waves A transverse wave vibrates up and down while the wave travels from left to right. A transverse wave vibrates up and down while the wave travels from left to right. These are the “normal” waves that people usually picture. These are the “normal” waves that people usually picture. A longitudinal wave vibrates left and right as the wave travels from left to right. A longitudinal wave vibrates left and right as the wave travels from left to right. These waves do not vibrate up and down. These waves do not vibrate up and down.

Transverse and Longitudinal Waves

Boundary Reactions As a wave travels, it sometimes moves out of one medium and into another As a wave travels, it sometimes moves out of one medium and into another This transition is called a boundary, and it might affect waves in 4 different ways This transition is called a boundary, and it might affect waves in 4 different ways 1.Absorption 2.Reflection 3.Diffraction 4.Refraction

Absorption Soft boundaries absorb waves. Soft boundaries absorb waves. This means that the waves energy dies out. This means that the waves energy dies out. Example: Yelling into a pillow. Example: Yelling into a pillow.

Reflection Hard boundaries reflect waves Hard boundaries reflect waves This means that the wave bounces off of the boundary’s surface This means that the wave bounces off of the boundary’s surface Example: Yelling against a wall Example: Yelling against a wall

Diffraction Corners diffract waves Corners diffract waves This means the wave bends around the corner This means the wave bends around the corner Example: Talking to someone around a corner Example: Talking to someone around a corner

Refraction Transparent boundaries refract Transparent boundaries refract This means that the wave bends when it moves into a medium that is faster or slower This means that the wave bends when it moves into a medium that is faster or slower Example: Light bends as it passes from air and into the glass of eyeglass lenses Example: Light bends as it passes from air and into the glass of eyeglass lenses

Constructive Interference When two waves meet, they can be added together if they are “in-phase.” This means that the high and low points of the wave are matched. When two waves meet, they can be added together if they are “in-phase.” This means that the high and low points of the wave are matched. When this happens the waves add together in a process called constructive interference. When this happens the waves add together in a process called constructive interference.

Destructive Interference When two waves meet, they can cancel each other if they are “out-of-phase.” This means that the high and low points of the wave are not matched. When two waves meet, they can cancel each other if they are “out-of-phase.” This means that the high and low points of the wave are not matched. When this happens the waves cancel each other in a process called destructive interference. When this happens the waves cancel each other in a process called destructive interference.

End of Intro to Waves Physical Science