DO NOW 1.What is in the police officers hand? What is it used for? 2.Is wave speed or wavelength and frequency more useful for differentiating among different types of electromagnetic waves? 3.The prefix infra- means below, and the prefix ultra- means beyond. Knowing this what do you think infrared and ultraviolet means?

THE ELECTROMAGNETIC SPECTRUM Chapter 12 Section 2

OBJECTIVE & ESSENTIAL QUESTION Describe waves in different regions of the electromagnetic spectrum Compare properties of electromagnetic waves Identify different types of electromagnetic waves How does wavelength, frequency, and speed change throughout different mediums?

FOLDABLE Using two sheets of loose leaf paper: Fold in half long ways Cut the TOP half of both sheets into 4 even sections Label as follows: The Electromagnetic Spectrum Radio Waves Microwaves Infrared Waves Visible Light Ultraviolet Waves X Ray Gamma Rays

ASSIGNMENT In groups of 4 to 5 people: Read your assigned section Complete that section of the foldable Be Prepared to teach the class about your section

THE ELECTROMAGNETIC SPECTRUM Electromagnetic waves are described by different names depending on their frequency and wavelength. Radio Waves Microwaves Infrared Waves Visible Light Ultraviolet Waves X Rays Gamma Rays

RADIO WAVES Low frequency electromagnetic waves Wavelengths longer than 1 mm Can carry an audio signal from radio stations to a radio Don’t hear radio waves Hear sound waves from compressional waves reaching our ears

MICROWAVES Radio waves Wavelengths of less than 30 cm Wavelengths of 1 cm to 20 cm are used to communicate Cell Phones Satellite Dishes Etc Heat food when interacted with water molecules in food Electric field vibrates => water rotates causing frictions => thermal energy => heats food

MICROWAVES (RADAR) RAdio Detecting And Ranging Find position and movement of objects Radio waves transmitted towards an object Measures time used for a wave to reflect to receiving antennas Used in speed guns, aircrafts, water crafts, and space crafts

MICROWAVES (MRI) Magnetic Resonance Imaging Uses radio waves to diagnose illnesses Use powerful magnet, radio wave emitter, & a radio wave detctor Protons in Hydrogen atoms in bones & soft tissue act like magnets & align with strong magnetic fields

INFRARED WAVES Wavelength between 1 mm and 750 billionths of a meter Used everyday by ALL objects Remote Controls CD’s Animals Etc Hotter objects emit more infrared waves Higher the temperature the shorter the wavelength

VISIBLE LIGHT Range of electromagnetic waves you can detect with your eyes Frequency and wavelength differ from radio waves Wavelengths of 750 billionths to 400 billionths of a meter Short visible wavelengths show blue Long visible wavelengths show red ROYGBIV All colors present shows as white

ULTRAVIOLET WAVES Wavelengths from 400 billionths to 10 billionths of a meter UVA rays: Longer-wavelengths that reach Earth’s surface UVB rays: Shorter-wavelengths cause sun burn UVA & UVB can enter skin cells Causing cancer, skin damage, & wrinkles (Negatives) Allows body to make Vitamin D (Positive) Makes materials fluoresce Absorbs UV light and reemits energy as visible light Used by police for fingerprinting crime scenes

ULTRAVIOLET WAVES (OZONE LAYER) Continually formed & destroyed by UV waves in the atmosphere Absorbs most of suns harmful UV waves Has been decreasing in recent years

X-RAYS Shortest wavelength Highest frequency Wavelengths between 10 billionths of a meter & 10 trillionths Used to form images of internal organs, bones, and teeth Used in airport screening devices to see bag contents

GAMMA RAYS Shorter then 10 trillionths of a meter Highest energy electromagnetic waves Produced in the nuclei of atoms