Archives September 2012

  • A balloon
Your vocal cords in your throat produce voice and your speech. When they are close together you tone sounds high and when their gap increases your tone becomes gruff. Let’s try one experiment to prove this. Take a balloon and inflate it fully:  now hold it with your fingers pinching the neck of the balloon. You will hear a shrill note coming out. Next start making the aperture gap bigger and bigger and you will hear the note getting more and more low as the  air escapes.

  • A single page of a newspaper
  Let us make a "paper pistol." It can be fun. The "pistol" can be made by folding a single sheet of a newspaper as shown in the illustration. Hold it from one corner and swing it rapidly in the air. A part of the paper comes out with a cracking noise as if a pistol is being fired. Fold the paper in half along its length and breadth. Now flatten it and fold the corners on the long side along the Length wise fold line. Now fold the whole paper in half to ensure that that the folded corners stay inside. It ought to resemble the illustration in Figure 3. The outer corners need to be folded towards you so that it continues along the midline as in Figure 4. Now turn the packet over as in Figure 5 folding it towards you in half along more...

  • A Torchlight
  • A beach ball
  Inflate a beach ball and stick a small paper shape onto It. Place the ball on a table. Darken the room and shine a beam of torch light (Sun) towards the ball .One half of the ball is lit up while the other remains in the shadow. Spin the ball to see how the shape passes from night to day as the earth goes around.   HOW DOES IT WORK? The light from the torch comes in contact with the half of the ball which is directly in the front and the light rays (travelling in a straight line) are unable to reach the other half of the ball which is thus left as a shadowed area. This is explains why we have day and night.

  • A sheet of white card.
  Mark 20 squares on a sheet of white card. Copy the picture into the squares. Take care to move the man up one step in each square and so on in the reverse order. Cut the squares and clip them in the correct order. Flick the cards to see the man walk up and down the flight of stairs.

  • A hair dryer
  • Two Ping-Pong balls
Place a hair dryer in such a way on the floor that the hot air is turned towards the ceiling. Now if you put two Ping-Pong balls in the blast of air, they two will hang in the air stream, as is shown in the illustration opposite. Pick up the ball which is higher. Hold it high, and let go into the air stream. The two balls will play hokey and change places even as they remain hanging. HOW DOES IT WORK? The two balls remains suspended in the air stream because water or air travelling at a high speed has lesser pressure than the water or air surrounding it. The hair dryer blast creates a column of fast moving air. The Ping-Pong balls floats because, as rushing air keeps them suspended, the still air surrounding the air  Column exerts more pressure keeping more...

  • Two pocket mirrors
  • A magazines
  Two mirrors put at a 60 – degree angle to each other helps make a kaleidoscope. A hexagonal patter is produced due to reflection of bits of coloured glass.  A Kaleidoscope can be made at home with two pocket mirrors. Take the magazine and place the mirrors on it. It should not be difficult to adjust them to a 60 degree angle by looking into the mirrors and moving them until you see a reflection that has six sides to it as in the illustration. Keeping the angle fixed move the mirrors on the magazine page. You will observe the constantly changing patterns of a kaleidoscope.       HOW DOES IT WORK? A symmetrical image is created by the 60 degree angle of the mirrors. This creates six reflections, each the mirror image of the more...

  • A large piece of card
  Divide a large piece of card by creasing it in 4 parts lengthwise. Cut slots into its side at exactly 45 degrees an inch inside the edge of the card. Also cut square windows as shown in the diagram. Fold the card along the creases and fix the last edge with tape thus making a square tube. Take two small mirrors and slide them into the slots with the reflective sides facing each other so that both are visible through the two windows you had cut. The periscope is now ready for use.   HOW DOES IT WORK?   Light coming in from the upper slots reflects off from the upper mirror towards the lower mirror. Since the viewer is viewing the image at the position of the lower mirror, he image is visible to him on the lower more...

  • A Magazine
  • Playing cards
  Flattern out a magazine on the floor. Hand over six playing cards to a friend. Ask him to drop each card from a few feet height. So it lands on the magazines. Show him how to hold a card, as shown in the illustration, but don’t tell him that the card has to be held vertically before it is dropped. If he holds the card vertically before dropping it, it will flutter to one side, missing the magazines. Now you show him the way to do it. You hold the card horizontally, so that the card is parallel to the floor. Let it go. The card will land on the magazines.   HOW  DOES  IT  WORK? When a card is dropped, gravity pulls it towards the floor. The surrounding air , however, resists its downward fall. Dropped horizontally, it more...

  • A square cheese cracker
  • A square of paper
  • A pencil with eraser
  • A pin
  Between the tips of your thumb and middle finger lightly hold the square cheese cracker. It will begin In rotate as you blow on it. Try and make a turning pinwheel. Take a 5-inch (11.25cm) square of paper, as shown in the illustration. Deftly fold the corners of the paper Insert a pin at the end of the pencil which has the eraser. Now flail the pencil around in the air. The paper square will start to rotate. Now try and pull the pinwheel in a backward position. It will begin to rotate in the opposite direction. Drag the pinwheel backward and it will spin in opposite direction.   HOW DOES IT WORK? Air pressure is created which pushes on the surface of the cracker once you blow on it. If the air pressure is more...

  • Two small, shallow glasses
  • A Ping-Pong ball
  You can make a Ping-Pong ball hop across from one glass to the other. Position   two  glasses beside each other. Drop a Ping Pong ball into one closet to  you in the illustration. Without touching the ball in any way let us see you get the ball into the other cup. Once  your friends have given up show them how. Just blow on the side of the ball nearest you. Given some amount of practice, you can make it fly from one glass into the other.   HOW  DOES  IT  WORK? It works because the air you blow down the side of the ball nearest you creates a pocket of compressed air that pushes the ball up and forward.


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