Waves and their Applications in Technologies for Information Transfer in Lego Mindstorms NGSS MS-PS4

What do I need to know about Waves? I must: 1)Know how our sensors use waves to provide input information about the environment. 2)Identify the parts of a wave. 3)Contrast a light wave with a sound wave. a.How are they similar? b. How do they travel? 4)Explain what causes “sound”

What is a wave? Wave – A disturbance that propagates through space and time, usually with transference of energy. Examples: Light, Water (mechanical), and Sound Video: (00:00-09:08) Waves; Sound and Electromagnetism

What is a wave? A simple wave has a repeating pattern with a specific wavelength, frequency, and amplitude. (MS-PS4-1)  Wavelength – The distance between two sequential crests, troughs or nodes of a wave.  Amplitude – The maximum disturbance in a medium during one wave cycle.  Frequency – The number of occurrences of a wave per unit time. ( Measured in Hertz )

Sound Waves  Sound waves are called compression or longitudinal waves  They compress particles which transfer energy along a path.  The wavelength is the distance between areas of compression  Video: Sound Wave Properties (0:00 – 3:40) Sound Wave Properties Wavelength Compression Waves can be represented as transverse waves using an oscilloscope

Sound Waves  Video: Sound WavesSound Waves  Compression waves require a medium to travel through.  Gas (air) allows compression wave energy to travel to your ear. (Human Hearing)  Slowest Speed  Liquids (water) – Whale communication  Medium Speed  Solids (rock) – Earthquakes  Fastest Speed  Video: Sound in a Bell JarSound in a Bell Jar  Video: What Does a Sound Wave Look Like? What Does a Sound Wave Look Like? Wavelength Compression (Longitudinal) Waves can be represented as transverse waves using an oscilloscope

Sound Waves  The frequency of a sound wave is determined by the number of compressions passing a given point per second.  High frequency sound waves = High Pitch  Low frequency sound waves = Low Pitch Wavelength

The Sound Sensor Our Sound Sensor: 1)Detects the amplitude of the input audible frequencies (frequencies that we can hear) 2)A threshold must be set to determine the high and low values. 3)Because the sound sensor detects amplitude (volume), the frequency (pitch) doesn’t matter. threshold

The Ultrasonic Sensor Our Ultrasonic Sensor: 1)Uses sound waves at frequencies beyond hearing. (ultrasonic waves) 2)It sends ultrasonic pulses out, they bounce off objects and return to the sensor. 3)The time that it takes to return to the sensor is used to determine the distance an obstacle is from the sensor. a.This is the same process bats use during echolocation Video: (09:08-14:05) Waves; Sound and Electromagnetism

Light Waves Video: What is Light?What is Light? 1)Light is made of electromagnetic waves. 2)They are transverse waves. (not like sound) 3)They are absorbed and reflected by objects a.Video: Light Absorption and Reflection Light Absorption and Reflection

Light Waves 1)Colors of visible light are determined by the frequency of the light waves. 2)Electromagnetic waves exist outside of our ability to detect and these are known as the Ultraviolet and Infrared regions of the electromagnetic spectrum. a.Ultra –” on the far side of, beyond” b.Infra – “below”

Light Waves 1)Do not need a medium (solid, liquid or gas) to travel through. a.It can travel through the vacuum of space i.Sunlight travels to earth. 2)Changing the medium causes light wave to reflect (bounce back) or refract (change direction) a.Video: Reflection and Refraction of colored light between Water (liquid) and Air (gas)Reflection and Refraction of colored light between Water (liquid) and Air (gas)

The Light Sensor Our Light Sensor 1)Can detect ambient light a.The natural light of the environment 2)Can detect reflected light a.Sends out a red light. i.Visible light in the red frequency. 3)A threshold must be set to determine the high and low values for reflected light. 4)Different colored surfaces reflect light differently. 5)The light sensor detects the brightness of the light reflected back to the sensor. a.Dark colors absorb more light – reflect very little. b.Light colors reflect a lot of light.

Wrap It Up 1)How do our sensors use waves to provide input information about the environment. 2)What are the parts of a wave. 3)Contrast a light wave with a sound wave. a.How are they similar? b. How do they travel? 4)What causes “sound”?

Wrap It Up 1.Energy is transferred from one place to another through waves. 2.All waves have a wavelength, frequency, and amplitude. 3.Waves move at different speeds in different materials. a.Air (gas) = slow b.Liquid (water) = medium c.Solid (rock) = fast

Wrap It Up Light Waves: 1.Are electromagnetic waves 2.Are transverse waves 3.Are reflected or refracted (bent) 4.Can travel through a vacuum. a.Ex. Sunlight to Earth Sound Waves: 1.Are produced when objects vibrate. a.Drum b.Guitar strings 2.Are longitudinal (compression) waves. 3.Cannot travel in a vacuum. a.Require some sort of medium to travel through (Solid, liquid and gas) a.Speed changes as the enter new medium