1. Electromagnetic Radiation

2. Waves… a review Most waves are either longitudinal or transverse.
Sound waves are longitudinal.
But all electromagnetic waves are transverse…

3. ? ?
Prompt students to guess what the teal box, then the blue box, is hiding. (Wavelength, Amplitude)

4. Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency
GAMMA RAYS
ULTRAVIOLET RAYS
RADIO WAVES
INFRARED RAYS
X-RAYS
MICROWAVES
VISIBLE LIGHT

5. Electromagnetic waves
Produced by the movement of electrically charged particles
Can travel in a “vacuum” (they do NOT need a medium)
Travel at the speed of
light c= 3.0 x 108 m/s
Also known as EM waves

6. What is the relationship between frequency and wavelength
What is the relationship between frequency and wavelength? INVERSE (as one goes up, other goes down)

7. Radio waves Longest wavelength, lowest energy Uses: TV broadcasting
AM and FM broadcast radio
Heart rate monitors
Cell phone communication
MRI (MAGNETIC RESONACE IMAGING)
Uses Short wave radio waves with a magnet to create an image
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

8. Microwaves Wavelengths from 1 mm- 1 m Uses: Microwave ovens
Bluetooth headsets
Broadband Wireless Internet
Radar
GPS
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

9. Infrared Radiation Wavelengths in between microwaves and visible light
Uses:
Night vision goggles
Remote controls
Heat-seeking missiles
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

10. Visible light
Only type of EM wave able to be detected by the human eye
Violet is the highest frequency and energy light
Red light is the lowest frequency light and lowest energy
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

11. Ultraviolet Uses: Shorter wavelengths than visible light Black lights
Security images on money
Harmful to living things
Used to sterilize medical equipment
Too much causes sun burn
Extremely high exposure can cause skin cancer
There is one more UV slide…

12. X-rays Uses: Tiny wavelength, high energy waves Medical imaging
Airport security
Moderate dose can damaging to cells
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

13. Gamma Rays Uses Smallest wavelengths, highest energy EM waves
Sterilizes medical equipment
Cancer treatment to kill cancer cells
Kills nearly all living cells.
Click the little rainbow box in the top right corner to return to the overview EM spectrum diagram

14. Waves or Particles
Electromagnetic radiation has properties of waves but also can be thought of as a stream of particles.
Example: Light
Light as a wave: Light behaves as a transverse wave which we can filter using polarized lenses.
Light as particles (photons): When directed at a substance light can knock electrons off of a substance (Photoelectric effect)

15. Emission of Light
Quantum – minimum amount of energy that can be gained or lost by an atom; can be referred to as a packet of energy
Photon – packet of light energy (quantum)

16. Electrons & Light ) ) ) ) ) ) ) 1 2 3 4 5 6 7 energy levels
5.1
Light & Energy
Electrons & Light
As energy is absorbed, the electrons move from their ground state (original energy level) to an excited state (higher energy level)
energy levels
Initial position
Final position
) ) ) ) ) ) )
nucleus
excited state
ground state

17. Electrons & Light ) ) ) ) ) ) ) 1 2 3 4 5 6 7 energy levels
5.1
Light & Energy
Electrons & Light
Electrons are unstable in their excited state, so they return to the ground state by releasing energy. During this return, light is emitted!
energy levels
Final position
Initial position
) ) ) ) ) ) )
nucleus
excited state
ground state

18. 5.1
Light & Energy
Spectra of Light
Emission Spectra - A set of frequencies of the electromagnetic waves emitted by atoms of the element
Shows all the wavelengths of light that are emitted
Spectroscope – instrument used to see the emission spectra
Unique to each element