-: MAKING A KALEIDOSCOPE :-

It is an optical instrument that forms beautiful patterns, It contains two mirrors which meet at an angle of 600. Light from coloured objects placed near the mirrors-bounces between them to form several reflections. The most fascinating aspect about the kaleidoscope is that you never get the same pattern twice. Designers of wall papers and fabrics make use of this instrument to get ideas for new patterns.

*** MATERIALS REQUIRED ***

• Take two rectangular strips of mirrors identical in size about 8 inches long and 2 inches wide. Take one cardboard piece of the same size as the mirror strips. Join the mirrors and the cardboard together to form a long triangular tube. The slivered sides of the mirrors should face inward. The angles between them will be 600. This angle will produce six symmetrical patterns.

• Cut a piece of tracing paper or plastic paper to fit over one end of the triangular tube and glue or tape It in place. 

• Take about 7-8 pieces of bangles of different colours. Put these coloured pieces In the tube. Then hold the tube upright so that the pieces rest on the tracing paper. 

•  Look down into the tube and see the pattern formed. The end of the triangular tube near the eye can be closed by a transparent plastic sheet or glass sheet. The pattern will consist of 6 IdentIcal sections. Shake the kaleidoscope to change the patterns.

 

-: MAKING A SLIDE PROJECTOR :-

A slide projector is an optical instrument used to see slides on a screen in an enlarged image. It makes use of a good quality magnifier and a light source. When light falls on the slide, its enlarged image is projected on a screen. This simple project will demonstrate the principle of projection. 

-: MATERIALS REQUIRED :-

• Take one magnifying lens of about 3 inch diameter and 50 cm focal length.
• Take one cardboard box with a deep lid and of the same height as that of the focal length of the lens. The other dimensions of the box are not important. In the center of the lid of the cardboard box, cut a hole to mount the lens. Then glue the lens in place 

• At the centre of the bottom of the box, cut a hole slightly larger than your slides.       
•  For the rear part of the projector, take the second box and make a hole in the bottom of this box of the same size as the hole in the front box. The two holes should line up with each other when the boxes are placed on their sides.

                     

• Join the two boxes by gluing the pieces of cardboard to the sides. Leave a small gap between the boxes for the slide carrier. 

                  

• Make the slide holder from a piece of thick cardboard. This is used to position a slide between the holes in the boxes. 

                        

                 

•  Set slide between two box.

• In a darkened room, project the slide on to a white paper or white wall by switching on the bulb. To get a sharp picture, adjust the focus by pulling out or pushing in the deep lid that holds the lens. 

               

-: MAKING A PERISCOPE :-

A periscope is an optical instrument with which a person can see around corners and other obstractions. It consists of a long tube with a reflecting mirror or prism at each end. The reflecting surfaces are parallel to one another. They are arranged at an angle of 45⁰  inside the tube. Periscopes are important instruments used in submarines and tanks. They are also used by soldiers in the battlefield.

-: MATERIALS REQUIRED :-

• Take a cardboard tube and two small mirrors. Use a small hacksaw to cut a section near each end of the tube. First make a horizontal cut to about 3/4 of the diameter of the tube. Now make two cuts at 45⁰ to the horizontal cuts. Use a 45⁰  set-square for guidance while making these cuts. 

• Glue the mirrors in places where the sloping cuts have been made. The silvered surfaces of the mirror should face each other so that light can pass through the instrument. 

-: MAKING DANCING OR DISCO LIGHTS :-

This type of dancing or disco lights are commonly seen in the movies or clubs.
These lights have charming colours dancing on the shirts or coats of performers.
You can make the dancing light with the help of this project. This is an inexpensive
project and easy to make.

*** MATERIALS REQUIRED ***       

•  Connect all the components on solderless breadboard as shown in the IMAGE. 
•  The positive wire of first LED in each series should be connected to the positive terminal of the battery. 
• After assembling all the components as per the circuit, as soon as you connect the battery, you will see the charming green and red colours. You can put a switch In the battery circuit. 

Try to make it on a small PCB so that it can be pinned with the pocket of the shirt.

-: 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.