Traveling in Waves Light is a form of electromagnetic energy that travels as a wave. Different wavelengths different colors
The Visible Light Spectrum Visible light combination of all colors of light Visible Light Spectrum: Separate into colors. Made of ROY G BIV
A World of Color Why do we see this red sweatshirt as red? All colors hit it, with MOST colors absorbed. But red is reflected back to our eyes!
A World of Color Why are the leaves of plants green? Why is my shirt black? If I were wearing a white shirt, why would it be white?
Reflection Light bounces back from an object at the same angle at which it encounters a surface Light bounces back from an object at the same angle at which it encounters a surface
Refraction The change of direction of a ray of light, sound, etc in passing from one medium into another in which its wave velocity is different. The change of direction of a ray of light, sound, etc in passing from one medium into another in which its wave velocity is different.
Light is Energy Frederick William Herschel (1738-1822) Wanted to know if different colors had different temperatures. Found there WAS a difference. and something more …
Invisible Colors Experiment showed a lot of heat where there was no light visible. “Infrared” beyond red spectrum Other end of the spectrum “Ultraviolet”.
Electromagnetic Spectrum All E.M. travels at the speed of light: 186,000 miles/second. Stars give off electromagnetic energy that we can use to study them.
Lines in the Spectrum One day, a scientist named Fraunhofer got some new, high purity prisms he ordered. When he used the prisms to look at the Sun, he saw dark lines.
Lines in the Spectrum That was until he figured out that those lines were really there and that he had just made an important discovery. It turns out that when things heat up enough, they give off light.
Elemental Light When an element is heated, it produces a unique color. This is how “neon” lights work. This unique color is caused by an equally unique spectra. For scientists, this acts like an elemental fingerprint.
Lines in the Spectrum When a pure element like hydrogen (or compound like water), is heated up, it gives of specific wavelengths (or colors) of light Also, when light passes through a cold gas, (H 2 ), it absorbs those same wavelengths (or colors).
Spectrum Types The color something is represents the colors it is giving off The color something is represents the colors it is giving off Emission Spectrum Represents the wave lengths that the light source is putting out Represents the wave lengths that the light source is putting out Absorption Spectrum Represents the wave lengths that are absorbed by the light source Represents the wave lengths that are absorbed by the light source
The Spectroscope How do we learn about stars? Scientists use the visible spectrum of stars to learn about them Spectroscopes: A tool that separates the starlight into its visible spectrum What do spectroscopes tell us about a star? The elements in the star, temperature, gas condition, magnetic field, and pressure