LIGHT/EMS NOTES

LIGHT = a type of energy produced by the vibration of electrically charged particles. Electromagnetic Spectrum = the full range of electromagnetic waves ex: gamma rays = shortest and radio waves = longest Shorter wavelength = higher frequency Higher frequency = greater energy So Gamma rays = most energy Radio waves = least energy

The Electromagnetic Spectrum in order from slowest to fastest The Electromagnetic Spectrum in order from slowest to fastest. THE STORY 1. Radio Waves = Went home and listened to the radio 2. Microwaves = I then made popcorn in the microwave 3. Infrared Waves = Put on my “snazzy” infrared goggles 4. Visible Light = But the visible light outside was too bright 5. Ultraviolet Light = THEN the ultraviolet waves hurt my eyes (sunburn) 6. X-Rays = so I had to go to the hospital to get x-rays (would never happen) 7. Gamma Rays = and the doctors fixed my eyes with gamma rays

EXAMPLES 1. Radio Waves = TV, Radio, Cell Phones 2. Microwaves = Radar, Microwave ovens 3. Infrared Waves = Radiator, TV Remote, Skin (why we can be seen with night vision goggles) 4. Visible Light = Stars, Light bulbs, Fireflies 5. Ultraviolet Light = Stars, OUR SUN (sunburn) 6. X-Rays = Look at bones, teeth, luggage 7. Gamma Rays = Radioactive material, nuclear explosions, supernova explosions – medical uses (can kill cancer cells)

OUR SUN PRODUCES 3 TYPES OF EMS WAVES Infrared (sunlight as heat) Visible (light) Ultraviolet (sunburn)

Visible Light is the only part of the spectrum that we can see It includes all the colors of the rainbow = ROY G BIV Red Orange Yellow Green Blue Indigo Violet Red = longest wavelength Violet = shortest wavelength When all the colors combine = white When all the colors are absorbed = black

PROPERTIES OF LIGHT (and all electromagnetic waves) Light spreads out in all directions from its source Light travels in straight lines called rays Light travels at the speed of light (300,000km/sec) (186,000mi/sec) Light can travel in a vacuum (empty space)

All electromagnetic waves travel at the same speed in a vacuum, but they all have different wavelengths and different frequencies. When light strikes an object, the light can be reflected, transmitted or absorbed. TTO Transparent – transmits most of the light that strikes it (water, air) Translucent – scatters light as it passes through (wax paper) Opaque – reflects or absorbs all the light that strikes it (wood, metal)

Refraction Refraction – when light travels from one medium to another, the light bends Ex= spoon in a glass of water. Index of refraction – measure of how much a ray of light will bend when it enters a material. Air = 1 Water = 1.33 Glass = 1.52

Interesting Facts The sky looks blue because when the light waves hit our atmosphere the nitrogen and oxygen particles scatter the waves It would look violet but the cones in our eyes perceive it as blue Mars sky looks red because of the iron rich dust storms Sunsets over the sea look orange due to the salt particles and red due to pollution Rainbows are because the light is traveling through 2 surfaces

Did you know…all rainbows are circular???