SCIENCE CAPSULES

        We know, the flow of electrons is electric current.  Electrons are said to be negative charge carriers.        In a molecular structure, if there is a vacancy for an electron,  it is called hole .  When an electron from somewhere in the structure fills-up  this hole, a new  hole will be created where the electron has just left.  Hence a hole can move opposite to the electron .  So the holes are said to be positive charge carriers.     In a germanium crystal, arsenic is infused.  We get electron rich material called N type (negative) material.  When boron is added to germanium, we get holes surplus P type (positive) substance.        A thin P type material is sandwiched between two N type material.  Now a transistor is made.  These three pieces NPN are respectively called emitter, base, and collector.      By co...

     Why the city like ship floats on the water?  For the simple question, the simple answer is ship is less denser than water.  Yes, really.  The ship is designed and shaped so that it average density (mass/unit volume) is less than that of water.  That is why the ship can only have ship-shape .  But the usual explanation is based on Archimedes principle.       In this article, we are going to speak about density, even though it appears to be elementary concept, it has deeper meanings.       Density indicates how much matter is really packed in the unit volume.  Common sense says, cotton package is lighter than a bar of iron.  Physics says, mercury is 13.6 times heavier than water.  That is, 1 cc of water weighs 1 gm.  But 1 cc of mercury weighs 13.6 gm.  Hence mercury is used in pressure-meters, thermometers etc,.      Osnium is the heaviest metal avail...

       We use remote control that triggers TV, AC, etc,. How it works?  How the eye's vision is communicated to the brain? How a bar code reader in a mall works? How the smartphone camera shoots a picture?      "When light waves, infra red rays, ultraviolet falls on certain chemicals like zinc, electrons are ejected out and electric current starts flowing".  This process is known as photoelectric effect .  It is instantaneous .  How can the waves push electron?  Can sound waves push an object?  No.  Can  stream of fire disturb a concrete wall? No. So there must be 'something' in the photoelectric effect.      Einstein investigated and proved that light waves sometimes behave like pockets of energy or particles called photons .  When one photon strike an atom in a material, one electron is ejected out instantly.  It is like throwing a heavy stone on the wall and forcing out ...

      A needle point, we may be able to observe by naked eye.  The bacterium is comparable to the needle point.  It can be observed clearly using microscope.  It"s size ranges from 0.5-5*10^-6 m (micrometer).    There are good and bad bacteria.  The diseases caused by bad bacteria can mostly be treated with the antibiotics.  Also, the bacteria can be filtered out by 'reverse osmosis' etc,.       Next we have virus in the size of 20 to 400 nano meters( 10^-9 m).  They are the smallest life on the planet.  There are no good viruses.  They cause common cold to AIDS.  Their symptoms can only be treated.  The body should have good immunity to survive.       Bacteria and viruses are made up of cells which in turn made up of molecules and atoms .  The molecules are in the order of nano meter.  So the nanotechnology means technology based on molecules....

     In our daily life, we usually measure mass.  What is mass exactly?  Put a small child on a swing and push it.  You can easily do it.  Seat a 80 kg man on the swing.  It is difficult to push him.  Hence,  mass is the measure of resistance given by the body to change its state or for its acceleration(inertia).   Mass can also be termed as a 'measure of inertia'.       But a weight is force on the body due to earth's gravity.  A body of 1 kg mass experiences 9.8 newton gravitational force. f = mg f = 1*9.8 newton Hence its weight is 9.8 newton. 1. A mass remains the same everywhere but the weight depends on gravity.  A man weighs less on the moon but very heavy on the Jupiter due to gravity. 2. When gravity zero, weight is also zero.  That is why astronauts feel weightlessness and float in the space.  But still they carry mass and inertia. 3. When a thing moves in very hig...

    Let us assume that you and your enemy belongs to the same town.(hope you do not have an enemy. Even if you have one, make sure he does not know about prime numbers).  Both of you have left the town for greener pastures and you both visit the home town periodically.  You do not want to meet or face your foe even accidentally.  How to choose the timings cleverly?  This is just an example with a  smile to understand the nature of prime numbers.        Suppose you choose to visit the town at every 17th day (prime number).  And your 'friend' select to visit every 10th day.  The visits will not mostly coincide because 10 is not the factor of 17.  For that matter, 17  is not divisible by any other whole number. Suppose you unwisely choose every 2nd day, 5th day,  20th day.  You are more likely to meet your foe face to face sooner or later.  It is because 2, 5, and 20 are mutual factors ...

       Think of old radio sets made of tube valves.  Transistors replaced valves and the radio shrunk to pocket size.  Then electronic circuits were replaced by silicon chips.  Hence the radio set shrunk further and embedded in smart phone today.        The miniaturization is more pronounced and visible in electronics.  but the phenomena happens in all the fields.        Fans, lamps,(CFL, LED), motor pumps, grinders, car engines, fordable umbrella, contact lenses, button cells, phones, speakers(ear phone), clocks, machines and tools and what not.  Everything has shrunk. ADVANTAGES OF MINIATURIZATION 1. It is affordable. 2. Space saving , raw material saving 3. less energy, less pollution. 4. It is portable  5. highly efficient. MOORE'S LAW "The law is the observation that the number of electronic components in a silicon chip (integrated circuits) doubles approxima...