COLOR By: Me

Color When you put sunlight into a triangular-shaped glass, you can break up the light into a spread of colors of the spectrum. White color is a combination of all colors. Black color is the absence of color.

Color The atoms an object is made of reflect or absorb particular wavelengths, this is what gives an object color. Example: a red object will reflect red wavelengths, but absorb all others. Some objects are made of a combination of other colors. A yellow daffodil can reflect red, green, and yellow, even if it appears yellow.

Color Some types of glass can only transmit one wavelength of color. Example: blue colored glass will absorb all other colors and transmit blue light.

Color The sky is blue because the molecules in the sky scatter blue light more effectively than the other colors (except violet, but we can’t really see the violet). This is called Rayleigh scattering Sunsets/Sunrises are red because the Sun gets further away from us at those times, allowing more Blue light to scatter away, leaving the red for us to see.

Atomic Spectra Every element has its own characteristic color when made to emit light (photons) When a gas of atoms is excited, you can use a spectrograph to see the emission lines, which are spectral lines corresponding to the energy required for electrons to move from one level to another

Atomic Spectra The spectrum a gas emits is called an emission spectrum On the other hand, stars emit a absorption spectrum. The star is an opaque object with gas surrounding it, so the missing lines are the lines atoms are emitting, but are absorbed by the gas.

Atomic Spectra If stars are moving, the absorption lines will be shifted because of the Doppler Effect. Astronomers identify a line, calculate the shift of the line, and find the velocity of the star

FINISH HOMEWORK Do the worksheet. Its two problems Finish the gnomework from last class: pg 419 1, 6, 7, 14, 20, 28 And also do pg 439: 6, 18, 21, 24, 25