List four members of the electromagnetic spectrum. Two examples are light and radio waves. S-58 How are electromagnetic waves different from mechanical waves?

SPS9 Students will investigate the properties of waves a.Recognize that all waves transfer energy b.Relate frequency and wavelength to the energy of different types of electromagnetic waves and mechanical waves. c.Compare and contrast the characteristics of electromagnetic and mechanical (sound) waves. d.Investigate the phenomena of reflection, refraction, interference, and diffraction. Chapter 18 The Electromagnetic Spectrum and Light

How are electromagnetic waves different from mechanical waves? What is the maximum speed of light? How do electromagnetic waves differ from one another? What is the dual nature of electromagnetic radiation? What happens as light travels farther from its source? 18.1 Electromagnetic Waves

Electromagnetic Waves – transverse waves that have a changing magnetic field and a changing electric field –Produced when an electric charge vibrates –Do not need a medium –Transfer of energy by electromagnetic waves is called electromagnetic radiation (EMR) 18.1 Electromagnetic Waves How are electromagnetic waves different from mechanical waves?

All electromagnetic waves travel at 300,000,000 m/s in a vacuum –Maximum speed in the universe –Goes slower in other media –186,000 mi/s 18.1 Electromagnetic Waves What is the maximum speed of light? Porsche 918 Spyder Plug in Hybrid 98 mpg 198 mi/hr (0.055 mi/s)

Electromagnetic waves still follow the wave equation –The speed is always 300,000,000 m/s –For vacuum – really close for air too, so we use the same number –If frequency increases, then wavelength decreases 18.1 Electromagnetic Waves How do electromagnetic waves differ from one another? v=f

Electromagnetic waves sometimes behaves like a wave and sometimes like a stream of particles –travels through a vacuum – particle because waves need a medium –Light refracts – wave because particles don’t bend their path as they change mediums –Einstein – photons – wave packets of energy 18.1 Electromagnetic Waves What is the dual nature of electromagnetic radiation?

A. What is the speed of light in a vacuum? B. If a light beam has a wavelength of 6.33x10 11 m, what is the frequency? S-60 How do electromagnetic waves differ from one another?

What waves are included in the electromagnetic spectrum? How is each type of electromagnetic wave used? 18.2 The Electromagnetic Spectrum

The electromagnetic spectrum includes many waves – the following are listed in order of increasing frequency, decreasing wavelength, and increasing energy. Radio TV Microwaves Radar 18.2 The EM Spectrum What waves are included in the electromagnetic spectrum? Infrared Visible Light Ultraviolet X-Ray Gamma

Radio Waves –Radio signals –TV signals –Microwaves Cooking, for a short frequency range Cell phone transmission –Radar ( RA dio D etecton A nd Ranging) Bounce off the object for distance Can tell speed using the Doppler Effect 18.2 The EM Spectrum How is each type of electromagnetic wave used?

Infrared Rays –Transfer heat –Sensed by heat sensors in your skin Visible Light –The range that human eyes can detect –ROY G BIV (red, orange, yellow, green, blue, indigo, violet) 18.2 The EM Spectrum How is each type of electromagnetic wave used?

Ultraviolet –Sterilizing items –Required to form vitamin D –Tanning and skin cancer X-Ray –Medical and safety –Can also cause cancers 18.2 The EM Spectrum How is each type of electromagnetic wave used?

Gamma Rays –Cancer treatment –Industry to check pipes –We are constantly bombarded by Gamma rays from the sun 18.2 The EM Spectrum How is each type of electromagnetic wave used?

List 6 members of the EM spectrum in order of increasing energy. S-61 What waves are included in the electromagnetic spectrum?

List 6 members of the EM spectrum in order of increasing wavelength. S-62 What waves are included in the electromagnetic spectrum?

What three types of materials affect the behavior of light? How does light behave when it enters a new medium? 18.3 Behavior of Light

How light behaves when it strikes an object depends on the material the object is made of Transparent – allows most of the light to pass through it Translucent – allows light to pass through, but scatters the light Opaque – either reflects or absorbs the light that strikes it 18.3 Behavior of Light What three types of materials affect the behavior of light?

A number of things can happen to light when it strikes a surface Reflection – the light waves bounce of the surface –Regular reflection – rays bounce off in an orderly patter Creates an image –Diffused reflection – no pattern Only color 18.3 Behavior of Light How does light behave when it enters a new medium?

Refraction – bending of light when it strikes a surface –Cause objects to look broken –Or even a mirage (light bending due to different temperature layers of air) Polarization – when light only vibrates in one plane –Reduces glare 18.3 Behavior of Light How does light behave when it enters a new medium?

Diffraction – bending of light around barriers –A hole will act like a new source of the wave –Ripple away from edge 18.3 Behavior of Light How does light behave when it enters a new medium?

What determines the color of an object? What are the primary colors of light? What are the primary colors of pigments? 18.4 Color

Color depends on –What the object is made of (what colors it will absorb or reflect) –The color of light that strikes the object 18.4 Color What determines the color of an object?

Primary colors – three specific colors that combine to create all possible colors –Red, Blue, Green (RBG) –These colors combine to form the secondary colors Yellow, Cyan, Magenta –The primary colors all combine to form White 18.4 Color What are the primary colors of light?

Pigment – a material that absorbs light –Paint –Primary pigments are Cyan, Magenta, & Yellow –Ink cartridge colors –They mix to form Black 18.4 Color What are the primary colors of pigments?