Light and Color test

Why do you see a rainbow of colors through a diffraction grating or prism?

A diffraction Grating works similarly to a prism. The plastic film actually has microscopic grooves in it. When the light strikes the grooves, it reflects back at an angle based on its wavelength. This allows you to see all the colors that make up white light. A prism works the same way, light enters the glass and based on the wavelength it gets diffracted different angles causing you to see a rainbow.

Red light on Cyan paper.

Black

A perfect red light shines on a perfect green piece of paper. What color would the paper appear.

Black because green is made by only green, this means the paper will absorb all colors of light exept for green. Since there is no green light hitting the paper, the paper will not reflect any light. This makes the paper appear black.

A single lightbox is pointed towards a white screen. A green and magenta acetate is placed in front of the slit. What color will appear on the screen?

Black or no light because magenta acetate only lets through red and blue, and green only lets through green, so no light would make it through.

A mystery backdrop has red light shined on it and it appears black. Then blue light is shined on it and it appears blue. What colors could the backdrop be?

Blue or cyan.

What are all the primary colors of pigment and what are the colors that result from them?

Cyan, Magenta, and Yellow. Cyan + Magenta = Blue Cyan + Yellow = Green Magenta + Yellow = Red

A single lightbox is pointed towards a white screen. A green and yellow acetate are placed in front of the slit. What color will appear on the screen?

Green

A mystery backdrop has red light shined on it and it appears black. Then blue light is shined on it and it appears black. What colors could the backdrop be?

Green or black.

How can you make blue paint if only given primary colors of paint?

Mix cyan and magenta.

A single lightbox is pointed towards a white screen. A green and red acetate is placed in front of the slit. What color will appear on the screen?

No light or black because green acetate only lets through green light. So the green light is the only light left, but then the light gets absorbed by the red acetate because red acetate only allows red light through. This means there will be no light coming through the acetates.

Why have artists historically used red, yellow, and blue as the primary colors of paint?

One reason is simple force of habit. Cyan and Magenta don't match our mental image of blue and red. These color concepts are deep-rooted from childhood. Another reason is Cyan Magenta and Yellow were hard to find for a long time. Also, artists do not make there own secondaries.

Red light on yellow paper.

Red

Name all primary colors of light and the secondary colors that result from them.

Red Green Blue Red + Blue = Magenta Blue + Green = Cyan Red + Green = Yellow

A green light and a magenta light are shined on a white screen. What color would appear where they meet?

White because magenta light is red and blue light and green light is green light. Red, blue, and green light mixed together creates white light.

A mystery backdrop has red light shined on it and it appears red. Then blue light is shined on it and it appears blue. What colors could the backdrop be?

White or magenta. The screen has to reflect red and blue light and the only paint colors that do that are white and magenta.

Two lightboxes that produce white light are placed a foot apart. They are angled so they hit the same point on a white screen. A green acetate is placed over one of them and a magenta over the other. What color will you see on the screen?

White, because magenta absorbs green and lets through red and blue. Green only lets through green, so red, blue, and green mix to make white.

A green light and a red light are shined on a white screen. What color would appear where they meet?

Yellow because green light mixed with red light makes yellow light.

Two lightboxes that produce white light are placed a foot apart. They are angled so they hit the same point on a white screen. A green acetate is placed over one of them and a red over the other. What color will you see on the screen?

Yellow because red and green light mix to make yellow light.