Archives September 2012

YOU  NEED:

• A Bunsen burner
• A glass tube
• A glass filled with water

  Imagine a siphon that works on its own! Don’t believe it? Try this experiment. Heat a glass tube over the Bunsen burner. Now bend the siphon into the shape shown in the illustration. Put it into a container of water, the tube turns into a siphon that drains off all the water from the container. There are many different self – starting siphons. But this is the simplest of the lot that have been invented. Some of these siphons date back to ancient Greece. How does it work? Once the water rushes through the tube to seek it own level, its inertia is sufficient to carry it above Bend B and make the siphon work.

YOU NEED:

• A tall glass
• A water jug or a pitcher
• Several table spoons of salt
• A fresh egg
• A spoon

  An egg can be made to float halfway down a glass full of water. Seems unbelievable? It can be done. Here is how to do it. Take the tall glass and fill half of it with water. Add several table spoons of salt and keep stirring until the salt is totally dissolved. Take the fresh egg and drop it in the glass. It will tend to float on the surface. Hold a spoon on the surface and ever so carefully pour fresh water over it. Use the bottom of the spoon to spread the water gently over the salt solution you have created. The egg now floats mysteriously in the middle of the glass which seems to hold just plain water. Place the glass on a shelf or the more...

YOU  NEED:

• A 5-Paisa Coin
• A bowl filled with water
• A paper clip
• Liquid detergent

The 5 paisa coin has aluminum as an alloy. It is so light that it can be made to float in water. Now fill a bowl with water. Once the water is still, balance a yen on a paper clip and carefully lower the yen to the surface of the water. It will float. Now let a drop of liquid detergent fall on the water- The yen will sink instantly. HOW DOES IT WORK? The surface of water can support objects that would normally sink. This is known as water's "surface  tension." Here water molecules attract each other. Water molecules attract each other. Molecules on the surface are always attracted to those beneath them. And as such the water molecules hold on to each other and prevent other objects from entering the water's surface. If you more...

YOU  NEED:

• A white flower such as a carnation
• Scissors (optional)
• 2 glasses of water
• Food colouring red and blue

Chances are that you have not seen a flower that is half red and half blue. However, it is easy to make one. Pick up the white flower and spilt the flower’s stem in half with the scissors or a fingernail. Cut off the ends of each stem. You need to fill up two glasses with water. In the first pour some blue food colouring till the water becomes dark  blue. Pour the red colour in the second glass. Dip the stems that have been split up in each glass, as in the  illustration. A few hours later, the white flower becomes half red and half blue!   HOW DOES IT WORK? The stem of a flower has many tiny tubes, half of which go to more...

YOU NEED:

• A piece of rubber tube
• A glass rode or piece of pipe
• Some masking tape
• Two bowls
• Some water

  The Greek mathematician, Archimedes invented simple method to pump water to a higher level and this was widely in use in the days gone by.           Try this. Wrap a rubber tube around a rod or a piece of pipe and then fasten it with tape as shown in illustration. Put the lower end of the pipe or rod in a bowl of water and keep rotating it. You will find the water travelling up the rubber tube and flowing out of the upper end into a basin or bowl held below it.   HOW DOES IT WORK? Water flows into the lower part of each coil of the rubber tube wrapped around the rod of pipe. With the rotating motion, the water – bearing more...

YOU  NEED:

• A paper or plastic cup
• A sheet of paper
• A sharp pencil

  A well known experiment can be switched around. The known experiment involves placing a sheet of paper over a glass which is half full of water. Then a palm is placed on top of the sheet of paper. The glass is turned upside down. The palm is removed carefully. You will observe that air pressure keeps the water from spilling out because the sheet is tightly pressed against the rim of the glass. The water pours out of the glass only at your bidding. The take off on this old experiment is a new one. Make a hole near the bottom of a plastic or paper cup. Repeat the Familiar experiment mentioned above over a basin or outdoors. Place your pointer finger on the hole to prevent air from entering above the water, and the paper will cling to the inverted glass. more...

YOU  NEED:

• Two glass jars
• Some hot water and some cool water
• A pencil
• Some thread

Take half a jar of hot water and dissolve as much alum as possible in the water. Cool the solution and pour it into another jar. Tie a small length of thread on a pencil. Suspend the thread from the mouth of the jar so that the thread touches the surface of the solution. You will find that a crystal will start forming on the end of the thread. If you leave it for a few days you will find that it will grow in size.

YOU NEED:

• A sugar cube
• A steel container
• A Match Box

Chemical reactions often require a catalyst to aid the reaction. To illustrate this, place a sugar cube on a plate. Try to set the cube on fire with a match stick. You will find that the cube will not burn. Then rub a little cigarette ash on the cube and it will immediately catch fire. HOW  DOES  IT  WORK? This happens because the ash works like a catalysts and helps in burning the cube. Remember a catalyst is an agent which helps in a reaction without changing its own state.

YOU NEED:

• Two Iron Nail
• One Nine Volt battery
• Two 18 inch lengths of wire
• A Cardboard
• One Jar containing Salt water

Connect two iron nails to a 9 volt battery with two 18 inch lengths of wire. Punch two holes in a piece of cardboard and pass the nails through them. Place the nails in a jar of salt water. Soon you will see that air bubbles begin to collect around the nails. Leave the apparatus for about 6 hours. You will see that the nail connected to the positive terminal gets coated with a thin layer of iron oxide or rust.

YOU NEED:

• An old test tube
• Water
• A cork
• A plastic bag

Take an old test tube with water and cork it. Place the tube inside a plastic bag and seal it. Place the bag for about 10 hours in a freezer. When you open the bag carefully. You will find that the test tube has cracked.