Visible Light

About Visible Light Visible light is a range of wavelengths on the electromagnetic spectrum that our eyes can see - less than 1% of the EM spectrum is visible light Visible light ranges in wavelength from approximately 400 nm to approximately 750 nm Visible light, and all parts of the electromagnetic spectrum, have all of the properties and undergo all of the same behaviors as every other type of wave - reflection, refraction, diffraction and interference

Polarization A light source (incident light) like a light bulb sends light waves out in all different directions and oriented in all different ways A polarizer is a filter that blocks out all of the wavelengths except those traveling in one direction. Incident Light Vertical Polarizer Vertical Light When two polarizers are placed on top of each other so that the directions of the filters are perpendicular, NO light can pass through the filters

Polarizing

Light Passing Through Objects When incident light hits an object, three things can happen, based on whether or not the object is transparent, translucent, or opaque. Transparent – light passes through an object Translucent – some light passes through, while other light is reflected or absorbed Opaque – all light is either reflected or absorbed by an object

Refraction Into Colors When incident light is refracted, due to change in speed, different wavelengths refract more or less We can refract light with a device called a prism The greater the frequency (shorter wavelength) greater the refraction Since our eyes see wavelengths as colors, violet gets refracted the most and red gets refracted the least. Therefore, from longest wavelength to shortest wavelength, the colors go ROYGBIV

Colours As shown by a prism, white light is made up of all colors and wavelengths of light. White light, however, can be made simply by combining the three primary colors of light, red, green, and blue All colors of light can be made with combinations of different amounts of red, green, and blue lights -- this is how TV screens and projectors work **Remember the three primary colors of light are different than the 3 primary colors of pigments!!!****

Color Mixing Chart Red White Light Magenta Yellow Green Blue Cyan

Using the Table Red + Green = Green + Blue = Blue + Red = Red + Blue + Green = White – Blue = White – Magenta = White – Green = White – Red – Blue – Green = Yellow Cyan Magenta White Yellow Green Magenta Black

What Color Objects Appear The colors that objects appear depend on the color of light that they reflect - for example, a red object reflects all red wavelengths, but absorbs all others If light is shined on an object that does not contain the wavelengths that it reflects, the object will appear BLACK. Examples: A green apple will appear green in yellow light because yellow light is made of both red and green lights! A green apple will appear black in blue light because blue light contains no green pigments!