Archives September 2012

  • Two straws
  • A glass of water
  Slide one straw into the glass of water. Put another straw beside it but outside the glass. Challenge a friend to put the end of the two straws in his or her mouth and drink some water. It just cannot be done! But you do it easily. The Secret : Just place your tongue over the end of the outside straw.   HOW  DOES  IT  WORK? When the straw on the outside is sealed by your tongue, you draw liquid through the straw but should both the straws be open you will draw only air.

  • An inflated balloon
  • A pin
  • A roll of cellophane tape
  Whenever you pierce a balloon, it is natural for you to expect it to burst. Surprise your friends by saying that you can puncture a balloon three times without it bursting. What they probably don't know is that there are two spots on an inflated balloon where you can push in a pin without bursting the balloon. The first spot is alongside the mouth of the balloon. The other is directly opposite the balloon mouth. A third spot can be created by attaching a small piece of invisible cellophane tape on the side of the balloon. The balloon will not burst when a pin pierces the tape. You have just shown that you have punctured the balloon at the three spots without bursting it. Complete the trick by pricking the balloon at another spot, other than the one with the tape. This more...

  • A large nail
  • A plastic bottle
  • A balloon
  • An unsharpened pencil
  Pierce a hole near the bottom of an empty hard plastic bottle with the nail. Spread a balloon over the mouth of the bottle, as in the illustration. Now inflate the balloon and put your thumb over the hole in the bottle. Unaware of the hole, your friends are puzzled because the balloon remains bloated. Hold the bottle at arm's length with the top of the bottle pointing to the roof. Insert an unsharpened pencil into the balloon and count till three. At three remove your thumb deftly from the hole. The balloon will deflate sending the pencil soaring into the air.    HOW DOES IT WORK? When the balloon is inflated inside the bottle and your finger covers the hole, at the bottom of the bottle, it a partial vacuum is more...

  • Two glasses
  Place the glasses one inside the other on its side on a smooth table top as shown in the illustration. Don't touch the glass yet separate them. This can be done easily by blowing strongly at the rim of the outer glass. You may not believe this, but the air is so compressed between the outer and inner and glass that the inner glass will slip free! The result is even more amazing if this is tried with paper or a Styrofoam cup. Place the nested cups in an upright position. Hold on to the bottom cup firmly and you blow on the rim. The cup inside will shoot up a foot or more into the air!   HOW DOES IT WORK? As you blow on the glasses, air travels between the rims to raise the air pressure inside the outer glass and the heightened air pressure separates more...

  • A bowl
  • A Table Tennis ball
  Drop a Table Tennis ball in a soup bowl. With your index finger start rolling the ball in a circular motion around the rim of the bowl. Onlookers would obviously expect the ball to stop rolling and come to rest at the bottom of the soup bowl. Surprisingly the ball will continue in its circular motion along the rim of the bowl for quite some time. Keep moving your finger along the rim of the bowl and it will seem that you have kept the ball in motion with some kind of magic.    HOW DOES IT WORK? Remember to keep your face close to the bowl as you run your index finger around the rim of the soup bowl. As soon as the ball hovers close to your mouth, quietly blow on it. Do it through pursed lips so as not more...

  • A bottle
  • A cork
  • Some water
  Take a bottle and a cork to fit the mouth of the bottle. Bore a hole through the centre of the cork and insert a drinking straw through it. Half fill the bottle with coloured water and cork it. Seal the joints with modeling clay. Put a small cap of modellingclay at the top of the tube and pierce as pin hole in it. Stand the bottle in a bowl of hot water.   HOW  DOES  IT  WORK? As the air inside the bottle heats up, it expands. Due to the expansion of the air. The water rises up and come out of the top of the straw like a fountain.

  • A plastic bottle full of water
  Make three holes lengthwise, one below the other, on the side of a plastic bottle. Block all the holes with a single piece of tap running from the top to bottom and fill the bottle with water. Remove the tape over all the holes. You will see that the water from the outlet at the bottom travels farthest while the one at the top is the closest to the bottle.   HOW  DOES  IT WORK? Water pressure depends upon the height between the surface of the water and the outlet that is provided to it. The streams for the bottle flow to different distances because the surface of the water on top of the bottle is exerting the highest pressure on the outlet at the bottom.

  • A jar
  • A candle
  • A Flat dish
  Light a candle in a shallow dish and pour water around it. Place a glass jar over the candle. After a while the flame goes out and water rises into the jar.   HOW  DOES  IT  WORK? The flame goes out because the oxygen in the jar is used up in the process of burning. The water rises into the jar to replace the used oxygen. When you look at the jar you can also see what percentage of the air is oxygen.

  • A bottle
  • Steel wool
  • A Flat Dish half filled with water
  Push some steel wool into the bottom of a bottle and upturn it into a dish of water. Leave it undisturbed for a few days. After a few days you will find that rust has set in on the steel wool and it has turned brown. The level of water also risen inside the bottle while it has reduced in the dish.   HOW DOES IT WORK? The oxygen in the jar has been used up in rusting and it has been displayed by the water in the dish. This shows that iron needs oxygen and water for rusting.

  • A page and a pencil
  Call your friends. Take the pencil and put it horizontally on the line that connects from X and Y as in the illustration. Your friends will maintain that the part of the grey rectangle below the pencil is a little darker than the portion of the rectangle above the pencil. Now remove the pencil to show them that the grey area looks exactly the same right through the rectangle.   HOW  DOES  IT  WORK? The subtle variation in the shades of grey does not register with the eyes. The eyes can distinguish it only when a pencil marks a spot halfway between the two grades.


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