-: MAKING AN ANEMOMETER :-

 An anemometer is an instrument used to measure the velocity of wind. The simplest anemometer has three or four cups attached to a vertical pipe. The wind catches the cups, spinning them around. The winds speed is measured by the number of times the cups go round in a certain period of time. Aeroplane pilots and sailors need to know the speed of the wind. A meteorologist makes use of anemometer for making weather forecasts.

*** MATERIALS REQUIRED ***       

•  Take one foot length of stiff wire.

       

• Bend one of its ends in the form of a loop.
• Fix this end at the bottom of the shoe box with tape.                                     

•  Place the lid on making a hole for the wire.
• Take two thin pieces of wood and make a cross

•  Push four paper cups onto the ends of the wooden cross, facing In a circle. 
• Tie a cotton thread to the pin in the side of the tube, leading it sideways over a roller. 

• Tie a small weight at the other end of the thread, just touching the ground.
•  Now, put the whole arrangement in a windy place and let the cups go. They should swing round in the wind. Use a watch to note the time, how long the weight takes to rise from the ground to the edge of the table. Now, divide this length by the time taken, and you will get, wind velocity. 

-: DEMONSTRATING THE PHENOMENON OF PHOTOSYNTHESIS :-

Green plants use energy from sunlight and carbon dioxide from the atmosphere to produce oxygen and food. This process is called photosynthesis. To demonstrate the process of photosynthesis, green plants can be used and the oxygen produced can be collected in a test tube. 

-: MATERIALS REQUIRED :-

•  Buy a couple of plants suitable for a fresh-water aquarium from any nursery.

•  Fill the test tube with water and keeping it under water, slide it sideways over the funnel.

•  Position the funnel and the test tube over the water plants. At this stage, the test tube should still be full with water. Put the trough in a sunny place and observe It for about three hours. The oxygen gas will come out from the plants In the form of tiny bubbles and rise up Into the test tube.

• Test this gas by burning a strip of magnesium, which bums more brightty in the test tube, confirming the presence of oxygen. 

-: MAKING A CHEMICAL GARDEN :-

A chemical garden is based on the process of crystal growth in the solution of water glass. It Is a garden with nonliving plants but that is very attractive.

*** MATERIALS REQUIRED ***

• Mix equal volumes of water and water glass and pour this solution into the aquarium tank.

•  Drop in the solution a few pieces of chemical salts, such as copper chloride, copper sulphate, copper nitrate, magnesium sulphate, aluminium sulphate, ferrous sulphate, ferrous chloride, alum, nickel sulphate, etc. These pieces should be slightly away from one another.

• Place the jar In an undisturbed place. After a few hours, attractive crystalline growths will appear as the chemicals react with the solution. Within a few days, a beautiful garden-type growth will appear In the jar.

-: MODEL OF A VOLCANO :-

The chemical volcano is based on the endothermic decomposition of ammonium dichromate. It portrays a volcanic eruption clearly.

• Take an asbestos wire gauge of 12 inch X 12 inch size. (It is available in your chemistry laboratory.)
• Build a volcanic cone with ordinary wet clay about 8 inch in diameter and 12 inch in height. Make a 2 inch deep cavity in the cone with the help of a wooden stick when the clay is wet. Dry it in the sun for two-three days.

•  Mix 65 gm of magnesium powder with 250 gm of ammonium dichromate powder.

• Put the asbestos gauge with the volcanic cone on a tripod stand and heat its central part with the flames of a Bunsen burner.
•  Pour some mixture into the cone of the volcano. The smoke with sparks due to, the formation of nitrogen will come out and give the appearance of a volcanic eruption.

-: MAKING A HOVERCRAFT :-

It Is a science toy which works on the phenomenon of the surface tension of water. It makes use of mothballs, which weaken the pull of surface tension in the water close to them. The stronger pull of the surface tension in front of each mothball pulls the sticks and the snowman spins in a circle.      

MATERIALS REQUIRED

• Draw a small snowman on the paper, color it and cut it out.
• Cut a slice of the cork about 1 inch thick and take four rectangular pieces of light wood. Make a small notch in each piece of wood. Glue one mothball In each notch In such a way that their surfaces remain In touch with water.

• Attach four sticks to the cork such that they are in the shape of a cross. At the free ends of these sticks, attach one wooden piece with glue.
• Stick the snowman to the slice of the cork.

• Take a plastic tub and fill It with water. Now, put the snowman Into the tub of water and watch It. The whole assembly will spin around due to the surface tension of water.

-: DETERMINING THE SURFACE TENSION OF WATER :-

Surface tension is a force that occurs at the surface of a liquid. The surface of a liquid due to the inward pull of its molecules acts like a stretched elastic membrane. This membrane can support light objects. For example, a blade can float on the surface of water. You can measure the surface tension of water by this simple project.

MATERIALS REQUIRED

• To measure surface tension, you have to make a balance device. For making the balance, take a wooden block and glue a wooden strip at Its center. Make the beam of the balance by using another wooden strip and using a pin as a pivot. 

• Take the iron ring and make a small bag of cloth. Tie three threads to make a pan of the balance.
• Take the plastic sheet and put a tiny hole in the centre with a needle. Tie a knot in a thread and use it to suspend the plastic sheet from one end of the balance.

• Use small nails on the other end to balance the plastic sheet. 

• Now, bring the bowl full of water and put it under the plastic sheet in such a way that it just touches the surface of water.You will see that the balance is disturbed. 

•  Now, add small nails in the pan until the plastic sheet suddenly breaks away from the surface of water. This extra weight is nothing but a measure of the surface tension of the water - the force with which it attracts the plastic.
• You can repeat the experiment by using mustard oil, kerosene oil, alcohol, etc. instead of water and measure their respective surface tensions also. 

More Example :-

• A razor blade or a sewing needle can be made to float on the surface of water, although these things are heavier than water. Put the blade or needle on a piece of blotting paper and then place it gently on the surface of water in a glass. The blotting paper soon gets drowned into the water and the blade or needle remains floating on the surface of water. This is due to surface tension.

• The nib of a pen is slit at the tip to provide the continuous flow of ink by surface tension. 

-: MAKING A WEATHER-INDICATING FLOWER :-

The amount of moisture in the air, i.e. humidity, can be used as the basis for forecasting the weather. When the humidity is high, rain is likely, while a low humidity usually indicates a dry spell. This project is based on the colour change produced in cobalt chloride by the moisture in air.

• Take a small sheet of blotting paper and cut it in the shape of a flower.

• With the help of cotton thread and a sewing needle, tie it with the thin wooden stick.

• Now take about 20 gm of cobalt chloride from a chemicals supplier or from your laboratory and make a strong solution of it in water.

• Dip the blotting paper flower in this solution, then put the flower in a warm place to dry.

• Now, your weather-indicating flower is ready for use. If the colour of the flower becomes pink on some day, it indicates a storm; if the colour becomes bluish-pink, it indicates rain; and if the colour becomes light blue, it indicates dry weather.