 A difficult question, thousands of years in understanding.  Very difficult to study, since it cannot be caught, and it is very difficult to measure.

 Light is a wave that travels through the universe’s electromagnetic field.  Electromagnetism = a combination of electricity and magnetism  Light waves do not need a physical medium like air.

 Frequency – light is caused by the vibrations of electrons  Wavelength – light waves have crests and troughs, just like water waves  Speed – the speed of light depends on what it is traveling through.

 299, 792, 485 m/s ≈ 3 x 10 8 m/s  186,282 miles per second  671 million miles per hour  Can be slowed if passing through water, glass, etc.

 Most light is invisible, because it has frequencies that our eyes cannot see.  Light with faster frequencies has shorter wavelengths and higher energy  Speed = wavelength x frequency  Wavelength = 3 x 10 8 m/s ÷ frequency

Type Ballpark Frequency Ballpark Wavelength Radio (AM)10 6 Hz300 minvisible Radio (FM)10 8 Hz3 minvisible Microwaves & Radar Hz3 cminvisible Infrared10 13 Hz.03 mminvisible

Type Ballpark Frequency Ballpark Wavelength Visible4.4 x Hz700 nmRed 4.9 x Hz600 nmOrange 5.1 x Hz580 nmYellow 5.8 x Hz530 nmGreen 6.3 x Hz470 nmBlue 6.9 x Hz430 nmIndigo 7.4 x Hz390 nmViolet

Type Ballpark Frequency Ballpark Wavelength Ultraviolet10 16 Hz3 x minvisible X-Rays10 17 Hz3 x minvisible Gamma Rays (from space) Hz3 x minvisible ???More?Smaller?invisible

A Spectrum is a continuous range

Another Diagram

Notice this backwards (?) diagram

The NECAP Version

 The only difference between types of light is how fast it vibrates (frequency)  Radio waves, visible light, and x-rays are all waves created by vibrating electrons at different speeds

 It can reflect! Reflection = bouncing off

 It can refract! Refraction = bending when it passes through

 It can disperse! Dispersion = separating frequencies of light

 It can diffract! Diffraction = spreading out and separating (by frequency)

 Light is a wave.  Light has frequency and wavelength.  The speed of light in a vacuum is 3 x 10 8 m/s.  It is the second fastest thing in the universe (only bad news travels faster).

 There are many types of light, which all differ only by frequency/wavelength  Faster frequency = shorter wavelength = more energy  In order: Radio, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays

 Light reflects (bounces off of objects), like on a mirror  Light refracts (bends while passing through objects), like through a glass  Light diffracts (spreads out and separates by wavelength), like making a rainbow