Ace Your Physical Science Project by Robert Gardner

Author:Robert Gardner [,]
Language: eng
Format: epub
ISBN: 978-1-4645-0498-3
Publisher: Enslow Publishers, Inc.
Published: 2010-04-08T04:00:00+00:00

FIGURE 14: An operating siphon

3.6

Experimenting With a Siphon

Materials:

fish tank without fish in it or other large container, filled with water

bucket or large jar

transparent plastic flexible tubing about 150 cm (5 ft) long

optional: giant dropper (baster)

Completely fill with water a length of tubing about 150 cm (5 ft) long, as described in Experiment 3.5, and start a siphon operating from a filled fish tank into a bucket or jar.

Lift up the bucket or jar into which the siphon is emptying until it is above the water level in the fish tank. Be sure that the ends of the tubing remain underwater throughout. What do you observe? After a short time, lower the jar until it is below the fish tank. Which way does the water move now? Try siphoning back and forth.

Raise the jar until the water level in the jar is slightly above the water level in the fish tank. How long does the siphon continue to operate?

Raise the jar again until it is completely above the fish tank. How long does the siphon continue to operate? When it stops, what do you observe has happened to the column of water on each side of the siphon?

Restart your siphon. Does the siphon work if the tubing droops below the catch bucket before entering it? Does the siphon work if the tubing has some loops in it above the tank? Can you make the siphon work with the 150-cm length of tubing looped as high up as possible?

What happens to the siphon if the end in the fish tank flips above the water?

When the jar is momentarily lifted above the fish tank, the siphon reverses direction, going from the jar to the fish tank. When the jar is placed below the fish tank, the siphon again reverses direction, this time withdrawing water from the fish tank. Then, when the water level in the jar is set higher than that in the fish tank, the siphon continues until both water levels are equal. At that point it stops, but it can be restarted if the jar is raised or lowered.

When the jar is raised above the fish tank and allowed to continue operating, its action continues until the jar is empty. At that point the water column breaks, and the siphon stops.

An operating siphon continues to work no matter how many loops are made in the tubing. The siphon works with a higher arch, too. If the end of the tubing in the fish tank flips out of the water, the column of water is broken, and the siphon stops operating.

If you were to allow the siphon to continue operating, it would empty the fish tank. This is probably the safest way to empty a fish tank. Of course, you would need to empty it into a larger container than the jar.

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