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Dowel Raindrop Model
# 6A46.26


Description: Three dowels are stuck into a Styrofoam ball. The Ball represents a raindrop, the big dowel a beam of light from the sun and two smaller dowels representing blue and red light. Use to show how a rainbow is formed with red on top even though blue light is refracted above the red when exiting the rainbow. Also use to show why the rainbow is an arc.

Instructions: Hold the Styrofoam ball on the chalk board and point the large dowel representing sunlight towards the room. Have a student volunteer hold the blue dowel towards their eye and while holding the large dowel perpindicular to the board, show where all the raindrops refract blue to the students position. Draw the blue arc on the board. Now ask where a drop would be that refracts red to the students eye. The would have to look up higher. Move the drop up until the red dowel is lined with the students eye and draw a new arc. The rainbow now appears on the board.

Hazards: Be careful while moving the Styrofoam ball and keep the rods a safe distance from the students eye.

Purchased/Built: built

Setup Time: none

Quant. in Demo Room: 1

Demo References
The Physics Teacher TPT 28(7),509 A rod and dowel raindrop model is used to show why a rainbow is bow-shaped.

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