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Exhibit Title

A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box in ambient light
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the blue light on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the green and blue lights on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the green light on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the red and green lights on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the red light on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the red and blue lights on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the red, green, and blue lights on
A box with red, green, and blue light bulbs, switches to turn each on or off individually, and a small post to cast a shadow
A view of the box with the red, green, and blue lights on with the post moved

Since the bulbs are in different positions, each one makes the post cast a shadow in a different position. Each combination of lights shows how colors of light mix to make other colors. Blue and green make cyan, green and red make yellow, red and blue make magenta. Shifting the position of the post can make the shadows overlap more or less, so you can see the colors closer together.

Materials

  • a long box
  • black paint or paper
  • wood dowel
  • wood slat
  • three light bulbs: red, green, and blue (LED bulbs work best)
  • three light bulb sockets
  • three switches (preferably a single unit with three switches on it)
  • a plastic gang box for mounting each switch
  • extra cardboard or other material
  • electrical wires
  • electrical cord with plug

Construction Instructions

Drill holes in the slat for the dowel to be placed. The holes should be deep enough that the dowel will stay in the hole without adhesive (you want to be able to move it). Glue the slat to the side of the box.

Wire the bulb sockets to the switches and the electrical cord. Mount the switches in the gang boxes. Construct an enclosure at one end of the box to mount the bulbs and the gang boxes. Space the light bulbs evenly vertically, offsetting the middle one depth-wise so the bulbs have a little bit of space for heat dissipation. Mount the gang boxes recessed a bit, so that the switches don't interfere with the box lid.

Paint the inside of the box black, or line with black paper. Put a white sheet of paper as a screen on one end of the box (laminated if you wish), or paint that side white.