Skip to main content

THE PHASE

   

    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 oscillatory motions are shown in the figure.

      We know, when a coil rotates in a magnetic field, alternating current(wave like) is produced.  If three coil rotates, we can generate three currents.  But they will be slightly out of phase due to the positions of the coils.  Hence we call them three phase current.

      Let a alternating current pass through capacitor or inductor, here the voltage and current will be out of phase by 90 degree.

      When light waves are 'in phase' they reinforce each other and produce highly energetic LASER.

      If  sound waves are out of phase, they destroy each other and produce silence.  A way to clear industrial noise.

      In synchronized swimming, the two swimmers are in phase perfectly.  

Comments

Post a Comment

Popular posts from this blog

THE EARTH, A SUPER ORGANISM

     JOIN MY COURSE: "Become a programmer in a day with python"       A man called 'love lock' (what a name) proposed a theory called Gaia theory, named after Greek Goddess.      It says, "Earth is a self-regulating organism like a human being.  The organic life in it interacts with in-organic matter and maintains atmosphere, temperature and environment".  Hence the earth is still suitable for the life to thrive.      Imagine, in a particular place, there are lot of flowers.  Some flowers are white and some are darkly coloured.  We know, white reflects light and heat while dark absorbs the same.  White flowers can thrive in hot climate.  But dark flowers requires cold climate.  The absorption and reflection balances and the environment reaches average, warm temperature at which both the flowers can co-exist.  This is the essence of "Gaia" theory.      On our earth, ...
3 comments
Read more

DISORDER IS THE "ORDER OF THE DAY"

         Imagine a balloon full of air.  The air molecules are moving randomly inside the balloon.  Let us pierce the balloon with a pin.  The air rushes out.  Why should not the air molecules stay inside the balloon safely and ignore the little hole?  That is not the way the world works.  The molecules always "want to occupy as many states as possible".  Hence the air goes out in the open to occupy more volume.   The things always goes into disorder (entropy) and the disorder increases with time.  The above statement is what we call "second law of thermodynamics".      Consider a cup of coffee on the table. Suppose the heat from entire room flows to your cup of coffee, the coffee will boil and the rest of the room will freeze.  Freezing means bringing things to order and arrangement.  It violates the second law.  Hence it will never happen.  Hence heat must flow from high ...
Post a Comment
Read more

CASINO'S GAME

           Let us find out how the casino survives with mathematics.      Say, your friend invite you for a game of dice.  You must bet (wager) 2 dollars.  If you roll 'six' you will get back 8 dollars.  The game will go on for 30 rounds.  All sounds good.      The probability of rolling 'six' is 1/6.  Since the game will be played for 30 times, the 'expected win' is 30*1/6 = 5.  That is, you are expected to win 5 rounds out of 30.  Hence your gain will be 5 * 8 =40 dollars.  ok.  This also implies that you will loose 25 rounds.  Hence your loss will be 25*2 =50 dollars.  Your net gain will be gain-less = 40-50 = -10 dollars. For 30 rounds, the loss is -10 dollars, Hence, for one round =-10/30 = -1/3 dollars.  There will be a loss of -1/3 or 0.33 dollars per round.  It is not a fair game.     Let us make a simple formula to calculate  'Pa...
4 comments
Read more