sciencecapsules

         We know, in this digital world, all the information is digitized(represented in binary using 1 s and 0 s).       Say, your plain text (SMS) is digitized as, Plain text:  1100101.... To encrypt the above message we build a key stream as given below. key stream:  1010110....   Here '1' means "change the corresponding bit (binary digit) in the plain text".  That is, 1 in plain text changes to 0 and vice versa. '0' means"leave the bit in the corresponding position as it is ". How it works: Plain text ; SMS: 1100101..... Key stream:          1010110.... Encrypted text:    0110011..... Here first bit in the 'plain text' is converted to '0' because '1' in the first position of key stream.  The second bit '1' in the plain text is left untouched due to '0' in the key stream. It goes on.....      The encrypted message now can be sent thro...

      Try to move a loose rock.  Try to catch a cricket ball.  Both will be difficult.  Starting a body at rest or stopping  a moving body requires force.  A body always resist the change.  The resistance level is proportional to the mass of the body.  This property of the body is called ' Inertia '.  So we can say mass is the measure of inertia or vice versa.      In earth, gravitational force acts on all the bodies.  We measure it and call it weight.  In space, in the absence of gravity, pure mass and inertia can be measured using artificial force.      Once we overcome the 'inertia' (resistance) and start the body, it is easy to keep it going.  That is why, starting of the vehicles and machines requires lot of energy.  The satellites are pushed( by rocket) once into the orbit and it keeps on resolving around the earth for number of years.     In rotationa...

            We see red or blue laser everywhere.  It is a highly useful modern day discovery.  What is actually Laser light?  Let us dig deep.      A candle emits light in all frequencies (colours) in all directions( composite light).  It is like crowd of people moving randomly.  A sodium lamp emits only yellow colour light (Monochromatic light).  It is like walking of uniformed soldiers , but out of step with each other.     A laser beam is a single colour (single frequency) light.  Most important, the waves are emitted in phase.(synchronized waves) and travel in unison.  Since the waves are in step with each other, they reinforce themselves and produce highly intense energetic beam of light.  It is like,column of soldiers marching in rhythm.  They all strike the ground with their feet in unison repeatedly.  So they may even bring down a bridge.   ...

      Frequency:  Number of oscillations or vibrations per second or no. of waves per second or no. of rotations per second or simply number of repetitions per second in a periodic motions. 1. Consider a pendulum.  Here no. of swings per second is the frequency.  It only depends on the length of pendulum or vibrating body.  So the length is the measure of frequency. 2. Consider a rotating wheel.  If you multiply frequency of rotations  with the circumference of the wheel, you get speed.  So frequency determines the speed. 3. Frequency of sound waves gives rise to pitch or tone.  A female voice has high frequency. 4. Frequency of electromagnetic waves decides its energy(E= h*freq.).  More frequency means more energy.  Radio waves, micro waves or light waves have small frequencies and they are not harmful to the human beings.  But X-rays, gamma rays, ultraviolet rays have high frequencies and they carr...

        The earth circles the sun in 365 days.  So the ancient people devided the circle into 360 degree.  And 360 is also the base of 60. Hence they felt comfortable.  We use this concept even today.  But there is more convenient unit called Radian.    Imagine the circle of unit radius. Here circumference = c= 2*pi*r=2*pi.*1 =2*pi                           c= 2*3.14 = 6.28     Hence, we can say, the total angle of the circle 360 degree(full circle) is proportional to 2pi.  or 180 degree(half circle) is proportional to pi.   90 degree(quarter circle) is proportional to pi/2. Hence we can measure the angle in  terms of pi. That is, we can measure the angle in terms of arc length in unit circle.This unit is called radian. 360 degree in radian is 2pi=2*3.14 =6.28....  hence 1 degree in radian is 0.0175 radian. ...

          The reduction-oxidation reaction pervades all chemistry and biology.  The name is nothing to do with actual reaction process.  Oxidation is the loss of electrons from the molecules and the reduction is the gain of electrons by the molecules.      An example :  We have seen festival fire works.  The festival crackers contains magnesium.  When the Mg is lit up, it burns brightly.  Here Mg reacts with atmospheric oxygen and produce magnesium oxide (MgO2).  Mg lost two negative electrons(oxidation) and oxygen gained the same 2 electrons (reduction).  Hence, positive ions of magnesium forms bond with negative oxygen ions.  Also energy is released as heat and light.  Here the 'Oxidation" name is justified.  Whenever there is oxidation,  reduction must also accompany it.       There are many examples for 'Redox' reaction like, extracting iron f...

       Imagine, a boat moving on the placid waters of a lake.  Initially, small waves will appear as the boat starts; big waves will build up as the boat pick up; the waves will overlap and superimpose on each other as the boat gains more and more speed; V  shaped wave formation appears. It is what we call "wake"(also shock wave) .   Here the point to note is "moving boat compresses the water waves".      The pitch of the siren of the speeding ambulance changes as it approaches us or recedes from us.  It is because the sound waves are compressed, (frequency increasing) in front of the vehicle and spread out (decrease of frequency) at the rear side of the vehicle.  This is called "Doppler effect".  The statement:  Whenever there is a relative  motion between the source of waves and the observer, the frequency of waves changes.  An important discovery in physics. ...

          Friction is an important phenomenon in our day-today life.  When you ignite a match stick, friction comes into play.      When there is a relative motion between two bodies, friction arises.  That is, when one body moves over the other, frictional  force develops.  Because of adhesive force between the contacting  surfaces, friction  develops.  Friction is proportional to the weight of the body that is moving and it is an opposing force.  It always acts opposite to the motion of the body.  That is , if you pull a,heavy table right side, friction will oppose the motion and act towards left side.  If you push the table left side, friction will shift towards right side.      Assume , a heavy iron safe is sitting on a rough floor.  The object weight acts on the floor, and the floor gives equal reaction on the iron safe.  Hence both the forces cancel eac...

       If you drop an object through the window of the fast moving train, it will follow a curved path and hit the ground.  Because, the object carries train's speed even outside the train and gradually slows down.  If you fire a gun from fast moving vehicle, you have to add vehicle speed to the bullet's speed.      Suppose, an express train's head light is switched on.  The light coming from the  lamp travels with its own speed, that is the speed of light.  You need not add the train's speed however fast the train may be.     Light is an electromagnetic wave.  Here "changing electric field is created by the changing magnetic field and vice versa".  Using this mechanism only , light wave progresses.  Hence the light wave propagation is independent of its source's  motion.     This electromagnetic process cannot be influenced by any other physical phenomenon.  So the light ...

     We are living in the three dimensional world (length, breadth, and depth).  Our two eyes facilitate to view everything in three dimension.  Our eyes are separated by a small distance.  Hence the two eyes see slightly different views of the same scene.  Consequently two different images falls on the screen of the eyes.  The brain process the two images and gives the three dimensional effect.      The digital camera takes a photo with only one lens.  So we get only two dimensional flat image and the depth is lacking.  How to produce 3D image?      Keep two cameras seperated by the distance same as our eyes.  Take two pictures of the same scene. Give greenish colour to one image and reddish colour to the other.  (software tools are available).  Print the two images one above the other or display overlapped images of both on a computer screen.      Wear colour...

       There is one Russian wooden doll. A large doll.  If you open the head, a less large doll is found inside.  If you take out the second doll and open it, another small  doll  appears.  If you open the third doll, another smaller one is found.  This goes on up to seven or eight dolls.      Suppose, you want to do some 'operation' with the dolls.  That is, you want to label each doll.  Take out all the dolls one by one.  Fix the label on the smallest one and put it inside doll which slightly bigger.  Label the second doll and repeat the operations till you label the biggest one.      This operation is laborious to do.  But we can write the command for the operation concisely as given below. Do "label the doll and also label the doll inside" Repeat until no doll is found.     There is a computer algorithm by name 'Recursion' simila...

      We know carbon exist in three forms namely Diamond, graphite, and amorphous carbon.  The carbon is also the main constituent of the soot and charcoal also.     Draw a line on a paper using graphite pencil.  The line is made up of several layers of carbon atom.  If one layer is extracted out, it is called graphene, a new form of carbon  Another avatar:  Laser was used to vaporize graphite.  Carbon clusters were formed.  One such cluster looked like soccer ball.  It is made up of 60 carbon atoms.  Hence the symbol is C60.  Here each atom bonded to three other carbon atoms in such a way that all the faces are pentagons or hexagons.  C60 shape is also called fullerens. Some properties of the buckey ball 1. It can withstand high temperature of about 650 c. 2. It can also bear lot of pressure. 3. cylindrical fullerens are also made.  They are extremely strong and useful in engine...

             Resonance is a very important physical phenomenon      Imagine  a swinging pendulum.  A 99 cm long pendulum makes one oscillation every two second naturally.  If you push the pendulum every 2 second, it will oscillate with long swing.  Now, the frequency of external force (pushing) matches with pendulum's natural frequency.  Hence it oscillates vigorously.  We say, "Resonance" has occurred here.  Suppose, you push the pendulum every one second or three second, it will only disturb the natural motion of the pendulum and may dampen the pendulum's oscillations.     The moon revolves around the earth in about a month.  In the same time, the moon spins about itself.  Here frequency of revolution and the frequency of the spin matches and resonance come into play.  That is why, the moon shows the same face to us always.     We have hea...

        To understand light, first we should understand maxwell's equations.  There are four equations.  I have given them in  words form below.    1. Single positive and negative electric charges exist.  The electric field flowing out from a charge is always proportional to the quantity of the charge.     2,   There is no single magnetic pole.  only magnetic dipole exist (north and south).  The magnetic field lines starting at any point around the North pole will always loop back and ends in south pole.  Hence the total field diverging out from a magnetic dipole is zero.            3. A changing electric field creates changing magnetic field which encircles the electric field and also acts perpendicular to it.      4. A changing magnetic field creates changing electric field which encircles the magnetic field and also acts perpendicular ...

         We know, minus multiplied minus yields a plus.  It is difficult to explain the logic behind it.  But there is a fun way to explain.  If you are my enemy(pardon me), your enemy is my friend. That is enemy's enemy is a friend.    We will see some real life examples.  If you owe a bank 3 dollars, it is indicated in your account as the - 3 dollars.  If 3 dollars is due to you, from bank it is indicated as +3 dollar.      So, Owe = -            due  = +    (for our understanding)      The bank credits some money to your account.  It is a positive operation.  The bank debits some money from you.  It is a negative operation.   So, credit = +          debit = -      Suppose, the bank debits 2 times from your account.  Each time 3 dollars that you owe to the bank.  Thi...

   We all know DNA stores bio-info. using which a life constructs itself.  The structure of DNA in unique and utilitarian.  It has the shape of twisted long going staircase and the information is coded in the rungs.  This spiral ladder is also called double helix structure.      Here the sides or strands are made up of phosphate and sugar molecules.T he rungs or the bases are made up of (nitrogen based molecules ) adenine-thymine pair and  guanine -cytosine pair which carries info.  DNA has around 3 billion bases.  Hence it is very long.  It made into super coil called chromosomes and stored in cell's nuclei compactly. Human's have  23 pairs of chromosomes.      DNA reminds us the old cassette tapes.  Audio and video are written on the tape in magnetic form, the tape is coiled and enclosed in a glass pool.      Let us see the advantages of the double helix. 1. The twiste...

        When we walk, both our legs are out of step.  That is, they cannot move together.  We say there is a phase difference of 0.5 between right and left leg.  When we hop and jump, the two legs move together.  They are in phase or the phase difference is zero.       In a childrens park, there are two swings.  Push one swing and pull another at the same time.  Then leave both of them free. They will oscillate exactly in opposite phase.  More exactly they will be 180 degree or pi radian out of phase.  What is the phase?  How to calculate it.      We know, rotation, oscillation and wave motion are similar.  When a point moves on circular path, the radius connecting it and the center sweeps angle from 0 to 360 degree or 2 pi radian.  The angles that are marked on the circle are the phase of the moving point.  The corresponding phases of the wave and oscill...

        Life's basic unit is the cell.   Cell is a bio-chemical factory.  Even a super computer cannot match its functions.  The cell is the package of chemicals.  The chemicals are held together by a membrane called cell-wall .  The cells are broadly classified into animal cell and plant cell.      Animal cell is covered by thin membrane, where as plant cell is clothed with thick and rigid membrane.(cellulose).  The cell communicate, transport and build using its wall.      The thick walls of plant cells has certain advantages.  It protects plant from dehydration.  (A tree has to stand in the scorching sun for a long time.)     The thick cell-walls help plants to build strong and rigid trunks.  Hence they are able to grow to meters of height.  Since they are not weak like animal, some trees live for thousands of years.  Trees have to sacrifice mobility to ...

       Imagine a point moving on a circular path.Also consider the diameter.  Connect the moving point and the diameter by a line  .  As the point circles, the line grows and diminishes both in the upper and lower halves.  Now cut the lower-half  and shift it by the length of the diameter.  You get a wave like form.  We can understand, as the point rotates, it can effectively produce waves in suitable environment. In Maths,waves can be represented by sine or cosine function.                  y=sin x As x changes from 0-360 degree or 0-2pi radian (a full circle), y values oscillates like a wave as shown in figure.  Now the sine function can  be modified to suit our needs.                  y=A sin 2pi n t A- Amplitude- Maximum height of wave. n- Frequency of rotation. t- instant of time.    Next, imagine a...

     To measure time, we need some periodic motions. The sun rises and sets regularly. This periodic phenomenon   used to measure time in those days. Sun dial was constructed and the shadow was used to indicate time. We know, the sun's apparent motion is not accurately periodic.     Then Galileo discovered the pendulum. The time taken by the pendulum for the oscillations does not depend on the mass suspended or the length of the swing but only depends on its length. A "one meter" (99 cm) long pendulum takes 2 seconds for an oscillation. So people constructed pendulum clocks which showed time for 270 years successfully.    Next came,  quartz crystal based clocks. When a tiny electrical voltage is given to a tiny fork like crystal, perfect vibrations are set in it. Exactly 32768 times a second. This precise frequency is the basis for measuring the second and the time. This electronic clock is definitely more accurate than pendulu...

      The word 'proportional' appears in almost all the physics laws.  Let us have a look at it.      Look at the above figures.  Here, as the diameter increases, so is the circumference of the circles. So circumference is proportional  to the diameter.   or C is proportional 2r         hence, there must be some relationship between C and 2r.  Or 2r is scaled to circumference by some number.  That number is called constant of proportionality, Therefore C= constant* 2r        or  Constant= C/2r     By drawing numbers of circles, measuring C and Diameter and dividing one by the other, we can arrive at the constant which happens to be 3.14...=pi    Finally,C = pi*2r                  C= 2*pi*r other examples, 1. force is proportional to the momentum : constant=1 2. current is proportional ...

          We know genes or DNA molecules stores biological information and transfers these information from generation to generation in species.  How the information is encoded in DNA?  We can compare it with electronic digital coding and understand.      In digital memory , the two symbols 0 and 1(bit) are basic elements.  In DNA, four elements adenine(A), cytosine (c), guanine(G) and uraul (U) are the fundamental units(chemical) to represent bio-info.      In digital, 8 bit (letters) words are used and they are called bytes.  2^ 8  = 256 symbols can be encoded using 8 bits system.  (today 32 bits, 64 bits are also common).  example: "A" is represented by 01000001 "=" is represented by 00111101      In  DNA, out of four, letters(ACGU), three letters are used to form words called codons.  So, 4^3 = 64 symbols can be represented in this way.  There are 20 a...

A software clock FOR I = 0 TO 24     ' hour    FOR J = 0 TO 60    "minute        FOR K = 0 TO 60    'second         one second delay          PRINT I ":"J":"K     'time         NEXT K     NEXT J NEXT I     The above small program displays time.      The I loop executes for 24 times to indicate the hour.  For each I loop, J loop executes for 60 times (minutes).  For each J loop, K loop is iterated 60 times (seconds).     So the command 'print' (display) is executed 86400 times in 24 hours.     So the loop iterates itself untiringly.  The loops can be nested to create complex process.  But they should be handled carefully and stopped properly.  Else they will slip into infinite iterations causing programming nightmares.      Mostly ...

    Seven is not too few or too many.  It is some appreciable and observable quantity.  It is the prime number( not divisible by any number).         We have seven musical notes using which millions of songs have been composed.  If we have three notes, it may be not enough.  If we have seventy notes, it may be confusing.     We have seven distinct colours in the rainbow or in the sunlight.  We see everything using the sunlight.  So these seven colours are responsible for our colourful world.     Long back, people were able to observe only seven celestial bodies like sun, moon, mars etc.  So they created seven day week.  5 days work, 2 days rest go well with us.  So we accepted it even though we observe nine planets today.      There are seven seas on the planet Earth.  The very famous south Indian temple is situated atop the seven hills.     A sev...

           When white light is sent through prism, it is split into colors.  A great discovery by Newton.  Raindrops acts like a prism and split sun light into seven colors forming the rainbow in the sky.          Let us go deeper into this phenomenon.      Take two carbon pencils (rods) both should be sharpened at one end.  Connect positive of high voltage to one rod and the negative to another.  Place the two pencils face to face so that there is a little gap between the sharpened ends.     Now powerful white spark will appear in the gap.  Actually carbon pencils burn.  This set up is called 'carbon-arc lamp' used as a light source in old cinema film projector.     If this light is sent through the prism, it split into spectrum of colors.  Since the light comes from carbon atoms, the colors can be called carbon spectrum.  (see photo).  The...

          Assume the electron (negative charge) moves perpendicular to a magnetic field.  Due to the motion of charged particle, another magnetic field is created around it.  The two magnetic fields interacts, and a force arises.  The electron is subjected to that force.      This force is called lorentz force given by the formula F = B.q.v      Force = magnetic field * charge* velocity of charge.      This force is the corner stone of electrical engineering.     Place a current carrying wire perpendicular to a magnetic field.  Since the electrons are moving in the wire, there will be Lorentz force on the wire.  The wire will be pushed or pulled according to the direction of the magnetic field.  This is also called 'Motor effect".      When a current carrying coil of wire is placed in a magnetic field, it will be pushed and pulled and rotations can b...