1. The Electromagnetic Spectrum Rainbows plus a whole lot more

2. Wave vocabulary

3. Colors of the rainbow? Violet Blue Green Yellow Orange Red

4. Describing light… Longer wavelength   Higher frequency  Higher energy

5. Describing light… Wavelength (nm)

6. More than meets the eye… Electromagnetic Spectrum

7. But what is electromagnetic radiation? Most waves require a medium. EM radiation does not. They can travel in a vacuum

8. Gamma rays X-rays Ultraviolet Visible Infra-red –“below red” Microwaves –Cell phones Radio waves High to low energy Ionizing radiation

9. Ionizing radiation Glossary Entry Subatomic particles or electromagnetic waves energetic enough to detach electrons from atoms or molecules, ionizing the atoms or molecules. Gamma rays, X-rays, high energy ultraviolet light, alpha particles, and beta particles are examples of ionizing radiation.

10. Uses for the Electromagnetic Spectrum

11. Your body emits IR radiation

12. Try it  Longer wavelength?   Higher frequency?   Higher energy? 

13. Spectrum of Electromagnetic Radiation Region Wavelength FrequencyEnergy (Angstroms)(centimeters)(Hz)(eV) Radio > 10 9 > 10< 3 x 10 9 < 10 -5 Microwave 10 9 to 10 6 10 - 0.013 x 10 9 to 3 x 10 12 10 -5 to 0.01 Infrared 10 6 to 70000.01 to 7 x 10 -5 3 x 10 12 to 4.3 x 10 14 0.01 to 2 Visible 7000 to 40007 x 10 -5 to 4 x 10 -5 4.3 x 10 14 to 7.5 x 10 14 2 to 3 Ultraviolet 4000 to 104 x 10 -5 to 10 -7 7.5 x 10 14 to 3 x 10 17 3 to 10 3 X-Rays 10 to 0.110 -7 to 10 -9 3 x 10 17 to 3 x 10 19 10 3 to 10 5 Gamma Rays < 0.1< 10 -9 > 3 x 10 19 > 10 5 ColorWavelength (nm) Approximate energy (eV) Violet 380-4502.76 Blue 450-4952.5 Green 495-5702.2 Yellow 570-5902.1 Orange 590-6202.0 Red 620-7501.65

14. Energy of the rainbow Violet Indigo Green Yellow Orange Red 2.76 eV 2.51 eV 2.2 eV 2.1 eV 2.0 eV 1.65 eV

15. ____ Ultraviolet ____ X-rays ____ Radio waves ____ Gamma rays ____ Visible ____ Infra-red ____ Microwaves Try it Rank in order of lowest to highest Frequency Wavelength Energy

16. Energy = Planck’s constant times frequency E = hν h = 6.62 x 10 -34 Joulessecond (Js) = 4.13 x 10 -15 electron Voltsecond (eVs) ν = frequency in Hertz (cycles/second) Also remember c = λν c = speed of light = 3.00 x 10 8 m/s So E = h c / λ Calculating energy

17. 1.Calculate the energy of a photon of infra-red radiation with a wavelength of 800 nm. 2.Your cell phone emits energy in the microwave region. Calculate the energy of a photon of cell- phone radiation with an wavelength of 10 cm. 3.The energy of a photon is measured as 4x10 -19 joules. In what region of the electromagnetic spectrum does it reside? (Hint: calculate in nm) Try it!!

18. Vocabulary Skills –Describe the electromagnetic spectrum using wavelength, frequency or energy –Rank energies of visible light –Rank energies of electromagnetic spectrum –Convert energy  wavelength, frequency  energy Concepts –EM radiation does not require a medium Can travel in a vacuum –EM radiation travels in packets called photons –Higher energy EM radiation ionizes atoms or molecules Stuff to know wavelength frequency ionizing radiation amplitude photon