Monthly Archives: November 2005

****Static Shock****

 

      The last few days have been particularly bad. Everytime I have stepped out of my car and put my hand on the door handle to close it, I have got that irritating shock. I always know that I am going to get it but then there seems no way out. And then a few days back I actually saw a spark when my fingers reached close to the door handle! And I recalled my high school Physics and remembered that a spark( caused by the electrical breakdown of air) needs atleast a 1000 volts!!!! Does this mean that when a person comes out of a car he has more than a 1000 volts of charge???? If it is true then isnt that dangerous??? How much charge does a person walking on a carpet acquire??? In today’s VERITAS we will recall static electricity and answer all these above questions.

      Lets take an ordinary piece of cloth. It is electrically neutral.

That means that the number of electrons and the number of protons are equal. Now lets take two pieces of cloth of different materials ( say one of silk and the other of wool). Now place them together so that they touch. SOme materials hold their electrons tighter than other materials. So if one piece of cloth touches another then the

proton(nucleus) of one material may come close to the electron of the other material and may try to pull it. The cloth that holds its electrons weaker may loose some electrons to the cloth that holds the electrons stronger( or closer). So one piece of cloth soon has more electrons than the other. So one piece of cloth becomes electrically positive and the other becomes negative. If you rub the two pieces of cloth with each other then more electrons and protons come in contact with each other and the more they pull at each other and more charge accumulates. If both the materials are insulators of electricity then they do not transmit charge. They store charge. So we have a charge accumulation without any current. This is static electricity.

      Now all this we have studied in high school. But how much is it?

If you walk rubbing your socks on a carpet you can acquire 20,000 volts in 20 minutes. On a winter day if you sit in a car for an hour and keep rubbing against the car fabric you could acquire 10,000 to 30,000 volts!

And I  am not talking about crazy amounts of rubbing. Just that much rubbing that happens when you drive for an hour! And then when you come out  of the car you are ****charged**** and when you touch the door handle there is a shock as 20,000 volts of electric potential get discharged!!!

So we are not playing with a 10 volt pappu charge. We are talking about thousands of volts!

      So how does a spark happen? When your fingers get charged to a huge amount and you place your fingers near the handle an intense electric field is build up between the fingers and the handle. The air molecules feel this huge electric field. Electrons are ripped from the air atoms because of this field. A electron that is ripped from the atom moves at an incredible speed guided by the electric field. On its way it hits more atoms and smashes more electrons from the atoms.

It creates a cascade of electrons which keep smashing against atoms.

Some electrons are recaptured and they loose energy by emitting light.

And we see a brilliant spark! So a huge amount of charge is needed to create this electrical breakdown of air and cause ths spark. And rubbing against the car fabric gives you that much charge!

      But is it dangerous? You may be charged to 20,000 volts but when you touch the car door handle you are discharged in a fraction of a second! You are discharged in about a millionth of a second or less. You could have been killed if it took a second or more. But it cannot because the 20,000 volts of potential difference is not maintained. In a house circuit the voltage of 220V is maintained and touching the wires for even 1/2 a second can kill you. So static voltage though it is so high cannot be dangerous because it gets discharged in a millionth of a second…. too little time for the body to experience anything significant. Only your fingers get hurt because of the spark. And there is a way to get over this pain: Dont touch the door with your fingers. When you get out of the car touch the door first using your car key. The spark will flow from the car key to the door and not from your fingers and you will be discharged in no time and after that you can touch the door with your fingers. So it is not the electrical discharging that hurts…. it is the spark that hurts because of the heat it produces in such a short time.

And using the car keys to discharge will make it much less painful.

Kanwar

 

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  Go, wondrous creature! mount where Science guides:                 

  Go, measure earth, weigh air, and state the tides:                 

  Instruct the planets in what orbs to run,                          

  Correct old time and regulate the Sun;                             

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Sudarshan, the Nobel Prize and some Philosophical comments

 

      It is that time of the year again. Every year in october the Nobel prize winners for the year are announced.

      A lot of people have asked me if there is a Indian born Physicist who “deserves” the Nobel prize. I always tell them about E.C.G Sudarshan.

      This year’s Nobel prize has gone to a group of Physicists who worked on quantum Optics. Among them is Roy Glauber. Glauber developed the mathematical representation of coherent states and used that to study light. And so did Sudarshan. Indeed coherent states are represented by what is called the Glauber-Sudarshan P representation.

      So Sudarshan missed the Nobel prize again. And he has missed it before in the theory of VA weak interactions. And he also discovered the Quantum Zeno effect and that too “deserves” the Nobel. In fact Sudarshan has been nominated for the Nobel prize six times and has missed it every time.

      E.C.G Sudarshan is a  great Physicist who has contributed a lot to the progress of Physics. And we Indians should be proud of him. About a fortnight ago there was an article in the “Hindustan times” that Sudarshan missed the prize because he was an Indian! Nonsense! Sometimes we attach too much importance to the Nobel prize and keep feeling bad that Indians dont win it.

      I know several other Physicists who have made fundamental contributions and not got the prize : David Bohm, John Bell, Klauder, Emil Wolf, Leonard Mendel, Berry, Aharonov …. the list goes on and on….

      How does it matter. We Indians should be more concerned that we are not producing as many scientists as we should. And our best minds are not going into science. Our best minds are only going into monetarily lucrative professions and not into Science.

      And should Sudarshan be sad that he missed it again? Absolutely not!

      A scientist has already received the biggest prize: a desire and the ability to understand this magnificient creation of God. This one thing can give him happiness all his life. The love and devotion for science makes every moment filled with pleasure. This one thing elevates his life to a higher level. Before this prize given by God, the prizes given by other men mean nothing.

      And a Nobel prize is not a reward for talent. Science does not progress because a few talented scientists make great discoveries. The progress of Science is a strange mixture of group effort and individual effort. Every scientist makes his individual effort in a direction that no body else takes. And one of these scientists finds the right answer. It is important that everyone takes his own individual path. Science progresses because there are a huge number of people who try to find the solution by taking different paths. So scientists should follow their own instincts and not follow the fashions of the day.

      And that is something that the Nobel prize hurts. People know that some subjects like cosmology, astronomy, interpretations of quantum mechanics may never yield them the Nobel prize and so they stay away from them. It may not happen at a conscious level but it does happen. This hurts science. And it is for this reason  that I personally would like the Nobel prizes to end. The concept of the Nobel prize does not help Science. Instead it impedes its progress.

 

      Some people say that Nobel prizes inspire the younger generation. This is not true. Nobel prizes just make some scientists famous without people actually knowing what they did. We Indians know about C.V Raman but how many know what Raman effect really is!? What is the point of becoming famous when no one knows what you did! The younger generation is inspired by good books. And any good book written by anyone has the power to inspire.

      The pursuit of science is almost a religious activity and when only when a religious activity has no reward associated with it does it become pure.

 

      The pure joy experienced by a Scientist when he pursues his Science are described the the following words by Bertrand Russel:

      “At the age of eleven, I began Euclid, with my brother as my tutor. This was one of the great events of my life, as dazzling as first love. I had not imagined there was anything so delicious in the world.