What it shows
A rotating or fixed sprinkler spreads water as small jets over a field. The model shows how water pressure, hole size and height decide how far and how evenly water falls.
The science
Water from a raised tank has pressure that depends on its height. That pressure forces water out of the small holes as jets, which break into drops and spread over the ground. Higher pressure and smaller holes give longer, finer sprays.
Materials
Cost: under Rs 200. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A 1 m plastic pipe or tube
- A bucket or bottle as the water tank with a tap hole
- A drill with a small bit, used by an adult, to make the holes
- A cork or cap to plug the pipe end
- Rubber tubing or a hose clip
- Several cups or tins for rain catchment
- A ruler and a measuring cup
Safety
For this project: An adult must drill holes, cut plastic and set up the raised bucket so it cannot tip. Work outdoors, and keep electrical items away from the water.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
Step by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
An adult drills a row of small holes, 1 cm apart, along one side of the pipe.
Close one end of the pipe with a plug and fix the other end to the tank with tubing.
With an adult, raise the bucket on a sturdy table or stool so the water level is one metre above the pipe.
Lay the pipe on the ground with the holes facing up at an angle.
Place catch cups in rows at 10 cm intervals and open the tap.
Run for two minutes and measure the water in each cup.
With the adult, raise the bucket until the water level is 1.5 m above the pipe and repeat.
Plot the depth in each cup across the distance and compare the two heights.
What you should see
Cups near the pipe collect more water, and raising the tank makes the spray reach further. The graph shows how evenly the model waters a strip.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
01Why does a higher tank spray farther?
Water pressure at the pipe is greater.
02What is uniformity of watering?
How equal the depth of water is across the field.
03Why use small holes?
They break the water into fine drops and save water.
04Where are sprinklers used?
On lawns, orchards and many field crops.
Take it further
Change the hole spacing and find the layout that gives the most even spread.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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