Rainbow powder

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• Take three types of powder: blue, yellow, and red. Put these in a container and fill it with water.
• Shake the container well, place it on a table, and wait for some time.
• The powder will form a rainbow, with red, orange, yellow,..., purple from top to bottom.
• The three types of powder used in this experiment are mineral pigments, specifically Rock Red No. 12 (small particles) and extra-coarse (large particles), Golden Yellow No. 6 and No. 7 (intermediate size), and extra-coarse Ultramarine (large particles). By exploiting the fact that the sinking speed of the pigments changes according to their grain size, the experiment created a rainbow of colors, and the resulting powder is called “Rainbow Powder”. The overlap between red and yellow produces orange, the overlap between yellow and blue produces green, and the overlap between red and blue produces purple. It is worth noting that the particle size of each color may vary between manufacturers, so multiple trials may be required to ensure accurate results.
• The container used here was about 2 cm in diameter, and a large container would require a large quantity of mineral pigments.

[Keywords]	Drag, water resistance
[Related items]	Mysterious powder
[Reference]	“Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, p. 72–75.

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