Articles

THE STORY OF ANAXAGORUS With a simple angle dangle meter we could measure how big is the earth. We did this by measuring the angle made by Dhruva tara with the horizon from two different places like Simla and Mumbai. We get two different results, because as you move north the angle increases. If you move north by 500 kilometres, the angle increases by around 4.5 degrees. Going around the earth you would traverse 360 degrees of latitude. By ratio and proportion you can work out that the circumference of the earth is around 40,000 kilometres. By the end of [...]

DISCOVER IT 6 If you have made all the things that I had suggested in the previous five articles of the series “Discover it” you are now ready to start measuring the universe. Let us see what we needed to start this science adventure : A plastic ball, a pocket mirror, some string, some stones, a piece of stiff cardboard. With the plastic ball we made a ball and ring mount. Fixing the mirror on this ball mount we made a solar telescope. With the string and stones we made an angle dangle meter to measure the angles of objects [...]

DISCOVER IT 5 At the end of ‘Discover it 3’, I had written that : “All the stars and planets move in the sky except Dhruva tara. Why ? The next thing you need to do is to measure the angle made by Dhruva tara above the horizon. Since Dhruva tara does not move, that angle is fixed. It does not change. This angle is just the latitude of the place where you are. If you are in Simla, or Mandi, you can measure your latitude by measuring the angle of Dhruva tara above the northern horizon. How do [...]

How to Make a Geosynchron. We learn in school that the earth rotates around its axis once in a day , and that it also revolves around the sun once in a year. A geosynchron model helps us to understand this. In my last article, Discover it 3, I promised to tell you how to make a geosynchron. Take a large spherical globe and place a tube through it as was described in my last article for doing the Dhruva tara experiment. You can use the plastic globe models of the earth which are available in most schools for this [...]

DISCOVER IT - 3 Last month we saw how to make a powerful solar telescope using a simple pocket mirror, a dark room, and a large plastic ball filled with mud or sand. I had asked you to do an experiment with this solar telescope to get a large image of the sun on which you might see sunspots. I also asked you to write back to Indradhanush describing what you did and what you saw. In this article, I was planning to tell you what you can learn by observing sunspots. But there is only one problem. So far [...]

THE SUN IN YOUR HANDS Remember the Magic Mirrors experiment I asked you to do last month. Did you perform the experiment ? If you did, then did you observe the following puzzling facts ? 1.When the reflected image is taken up on a nearby screen, it is the same shape as the mirror. Like this : ( Here put figure of a circle, a square and a triangle ) 2.When you take the image on a wall far away, all the images are round in shape , like this ( here draw three circles). Since you are all [...]

DISCOVER IT - 1 This year is being celebrated as an important anniversary year for science . One century ago, in the year 1905, young Einstein published four pathbreaking papers in physics. Each of these papers was of historic importance. In honour of this great year in the history of Physics, we are celebrating its centennial as “The International Year of Physics”. Here at Indrandhanush we will be observing this year in a special way, with a journey of discovery. Would you too like to become a great scientist, like Einstein, or Archimedes, like Aryabhata, Marie Curie or C.V.Raman [...]