SCIENCE CAPSULES

         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. ...