Build a Solar Water Purifier

Salty water such as seawater is usually considered not drinkable.  The process of removing salt and other non-volatile impurities from salt water is called distillation. A solar water purifier uses the greenhouse effect to trap energy from the sun.  The mechanism of solar water purifier also demonstrates the water cycle that naturally occurs on earth: evaporation, condensation and precipitation.

Materials you will need:

• A big bowl
• A plastic cup which is 1’’ shorter than sides of the bowl
• Clear plastic wrap
• Tape or rubber band large enough to go around the bowl
• Small rock or weight
• Salty water

Step-by-step instruction:

1. Put salty water in the bowl.
2. Place the plastic cup (with no water inside) in the center of the bowl.
3. Cover the bowl with plastic wrap and use either tape or rubber band to secure the plastic wrap.  Make sure the plastics warp is tight.
4. Put the small rock or weight in the center of the plastic wrap.  The extra weight in the center will ensure that the evaporated water will drop into the cup.
5. Place the bowl under the sun and observe how distilled water start to accumulate inside the plastic cup for every hour or so.
6. When there is enough water in the plastic up, open the plastic wrap and taste your purified water.
7. Can you tell whether the water taste differently from tap water?  If so, can you explain why?

idea-2 school project: wind turbine model

wind turbine model :
This wind turbine model makes its electricity with a simple generator which produces pulses of current, or
alternating current. It does so by passing strong magnets over coils of fine wire. Each time a magnet passes
over a coil, the coil becomes energized with electricity. With 4 coils connected together in series, the result is a
quadrupling of the voltage.
This is the simplest and possibly most efficient way to generate electricity, and is the same basic principle used
in almost all wind turbines, even the large scale commercial ones. The electricity from a wind turbine varies with the wind speed, so to make practical use of it, you must be able to store it in batteries, or change it into a form that gives a stable, constant voltage. Usually, electricity from wind turbines is converted from alternating current to direct current, which can be used for battery charging.

click the link below to down load pdf file

https://docs.google.com/fileview?id=0ByemygYrOVAdMmI1MTM0YzctNGUyMC00ZjFmLWJkNjMtZDlkZTBmY2I1NjYy

idea-1 Archimedes' Screw pump

Archimedes' Screw pump While in Alexandria, he invented a device now known as Archimedes' screw . It was first used to pump water out of ships and was later used in irrigation. This type of water pump is still used in many parts of the world today. Its very simple project model for viii and ix. A long, helical pipe if tilted 45 degrees and the lower end is inserted in water then Rotating the pipe moves water up to and out the top.