Azra in Pakistan

Hazara refugees from Afghanistan in Quetta and Peshawar Pakistan, along with their Pakistani Hazara (native, 3rd and 4th generation) brethren, have set up a remittance economy which has led to the opening of foreign money exchange places to handle the currency coming in. In Pakistan most of the Hazaras live in and around the city of Quetta, Hazara town and Mehr Abad where they hold high positions in the government of Balochistan, the federal government, and the Police force. A Hazara girl named Saira Batool became the first women pilot in the Pakistan Airforce. In Pakistan, Hazaras are mostly in business and have high education levels. They are integrated into the local social dynamics of the respective areas they have settled into and operated several successful trades and business. Hazaras are also politically active in Quetta and have a political party known as the Hazara Democratic Party.^[28] Other notable Hazara settlements can be found in Karachi, Lahore and more recently in Multan.^[29] The current Minister of Quality Education & Clean Drinking Water in Balochistan is a Hazara and having a Member in the National Assembly. The most notable Hazara in Pakistan was General Musa Khan, who served as Commander in Chief of the Pakistani Army between 1958 to 1966. On January 26, 2009, Hussain Ali Yousafi, chairman of the Hazara Democratic Party, was shot dead by Lashkar-e-Jhangvi in the southwestern city of Quetta.^[30]

Quetta history at night

Quetta (the word derives from kwatta, Pushtu for fort) is a natural fort, surrounded as it is by imposing hills on all sides. The encircling hills have the resounding names of Chiltan, Takatoo, Mordar and Zarghun. Quetta was first mentioned in the 11th century when it was captured by Mahmood of Ghazni on one of his invasions of the subcontinent. In 1543 the Mughal emperor Humayun rested here on his retreat to Persia, leaving his one-year-old son Akbar until he returned two years later. The Mughal

ruled Quetta until 1556, when it was taken by the Persians, only to be retaken by Akbar in 1595.

The powerful Khans of Kalat held the fort from 1730. In 1828 the first westerner to visit Quetta described it as a mud-walled fort surrounded by 300 mud houses. Although occupied briefly by the British during the First Afghan War in 1839, it was not until 1876 that Quetta came under permanent British control and Robert Sandeman was made political agent in Baluchistan. By the formation of political party of Muslims (Muslim league) Balochistan paid its contribution for the freedom of Pakistan. Qazi Muhammad Essa was the first man introduced Muslims political party in Balochistan, his father was Pashtun and mother was hazara, this struggle persisted until 1947. After the freedom, Balochistan was badly deprived of its legal rights resulting in Balochistan being the most backward province of Pakistan. Quetta especially, was pushed into fire of sectarianism after the dictatorships of Ayub Khan, Yahya Khan and Zia ul Haq

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Sound

Sound
Sound
               Sound is form of energy.
Production of Sound
               Sound is produced by all types of vibrating objects.
Nature of sound propagating
                         Sound is a example of mechanical wave. Which need medium for their propagation. The sound energy vibrates the participles of the medium parallel to the way of propagation.

The sound waves propagate through medium due to difference of pressure at different regions of the medium. The portion of the medium where the pressure is high called compression. And the region where pressure is low called rarefaction.
So the sound waves propagate in the form of compression and rarefaction. Sound wave is also called longitudinal waves.
Characteristics of sound
         Basically the sound possessed the following main characteristics.
    loudness of sound
    Intensity of sound
    Pitch of sound
    Quality of sound
Loudness of sound
             The differentiation between the faint and loud sound is called loudness of sound.
Loudness of sound depends upon the five main factors.
  1)       The amplitude of vibrating objects.
  2)       The direction of medium.
  3)       The distance between the observer and transmitter
  4)       The area of vibrating objects.
  5)       The temperature of the medium and condition of observer.
Intensity of sound
Definition
         The number of sound wave passes through cross sectional area (A). The cross sectional area held perpendicular to the way of propagation of the sound waves. The Intensity of sound is independent of the loudness of sound. Intensity of sound is denoted by (I).
Derivation
                The sound energy (E) passing through any cross sectional area (A) in given time (t). The cross sectional area (A) must be perpendicular to the way of propagation.
 Intensity of sound=Sound Energy/Area*time
 I=E/A*t
 Energy=Work
  E=W
 I=W/A*t
 I=W/t*1/A
As power=Work/time
 I=P*1/A
 I=P/A
Weber Fechnar Rule or Law
                          Weber Fisher law makes relation between the intensity (I) of the sound and its loudness (L). This stated As That
 The loudness (L) of the sound is directly proportional to the (Log ) of the Intensity (I).
 Mimetically
 Loudness Log (Intensity)
 L Log I
 L=constant Log I
 L=K log I
       Where If intensities varies by amount of 10, 100, 1000, 10000 ... Then loudness varies by amount of 1, 2, 3, 4. .... And (K) is the constant of proportionality which shows that the ratio between (L) and (I) are always constant.
Threshold of hearing
Threshold of hearing=Faintest audible sound
 I=10 -12Wm 2= 0 Decibel (db)
So we use Decibel denoted by (db) is the unit used to measure intensity of sound.
Intensity level or sound level
                The difference between the loudness of two sounds is known as the Intensity of sound level. It is denoted by Delta L
Pitch
          The differentiation between the grave (loud) and shrill sound is know as Pitch of the sound. Pitch of the sound depends upon the frequency.
  High frequency sounds have high Pitch.
  Low frequency sounds have low Pitch.
Example
            Women have higher Pitch. Where as men have low Pitch. The high Pitch sound moves fast ad travel high distance as compare to low Pitch.
Quality of sound
                            The differentiation between two same identical waves (same wave length, same amplitude, and same frequency) but the sounds are produced by two different instrument. This is due to the difference of the shape of the sound waves which is produced by two instruments.
Music and Noise
  Music
           The sounds which produce pleasant effect on the sense of hearing is known as music. OR The sound which changes gradually its frequency, wave length and amplitude is called music.
 Noise
            The sound which produced unpleasant effect on the sense of hearing is known as noise. OR The sound in changes suddenly is called noise.
Speed of sound
                      It is a devise which is used to find out the approximate value of speed of sound.
Resonance force
                     When two identical waves interact with each other and there frequencies match with each other, they reinforce each other and the resultant frequency is the sum of two waves which is known as resonance force.
Audible frequency Range
                         We know that sound is produced by a vibrating body. A simple pendulum also vibrates but it does not produce any sound. The reason is that its vibrations are very slow. A human ear can hear a sound only if its frequency lies between 20Hz and till 20,000Hz. Sounds of frequency beyond 20,000Hz are inaudible because the eardrum can not vibrate so rapidly. The audible frequency range differs a little for different persons. And it also decreases with age, Young children can hear sounds of 20,000Hz frequency, but old people can not hear sounds even above 15,000Hz frequency.
Ultrasonics
                  We know that human ear can not hear sounds of frequency less than 20Hz or more than 20,000Hz. Sounds of frequency higher than 20,000Hz, which are inaudible to human ear, can be produced and utilized many useful ways. Such sounds are called ultrasonics.

Wave and Motion

Wave
          A mechanism by which energy can transfer from one region to another region through medium without the actual movement of the medium itself.
Basically waves are classified into two main groups.
       1) Mechanical wave
       2) Electromagnetic wave
Mechanical wave
  Such wave which need medium for their propagation. Like sound wave, water wave, string wave.
  Mechanical waves are divided into two types.
       1) Transverse wave
       2) Longitudinal wave or Compressional wave
Transverse wave
Such mechanical wave whose particles are perpendicular to the way of propagation. Like water wave or string wave.
Longitudinal wave or Compressional wave
                                 Such type of mechanical wave in which the particles of the medium is parallel towards the propagation. Like sound wave. It moves due to compression and rare faction. At the region of compression pressure is high where as the region of rare faction the pressure is low. So due to this P.D the wave moves.
Electromagnetic wave
            Such wave which don't need medium for their propagation, like light wave and radio wave.
Electromagnetic waves are transverse waves.
Characteristics of wave
      There are some characteristics associated with the wave motion.
           1)   Wave length
           2)   Amplitude
           3)   Time period
           4)   Frequency
           5)   Velocity
Wave length
  The distance between two consecutive crest or trough is known as wave length. It is denoted by (l). The unit used to measure wave length is meter (m).
Crest
  The portion of the wave above the equilibrium position is called crest.
Trough
  The portion of the wave below the equilibrium position is called trough.
Vibration
  A complete round trip of wave is called one vibration or one cycle.
Amplitude
  The peak value of wave on either side of the equilibrium position, or the maximum height of the wave from equilibrium position is called amplitude.
Time Period
  Time of one vibration or time interval needed for a wave to complete one vibration or one cycle. Time Period is denoted by (T) and its unit is second (s).
Frequency
  The number of vibration passing a point in unit time is called frequency. It is denoted by (f) the unit used to measured the frequency is hertz (Hz), cycle/second (c/s) or Vibration/second=vib/sec or the reciprocal of time period
Hook's Law
  Hook's Law is applied on elastic object like spring or rubber..... This is stated as, if the spring (elastic object) are stretched or compressed by external force (Fext). Due to external force object displaced or produce displacement (x) in the spring. So the external force has done work.
So the work is done and store is the spring in the form of elastic restoring force (Fr) and the elastic restoring pull back the spring to its original position. The magnitude of restoring force is directly proportional to the displacement and opposite in direction to that displacement.
Mathematically:
  Fr a -y
  Fr=constant (-x)
  Fr=k(-x)
  Fr=-kx
Simple Harmonic Motion (S.H.M)
  It is a type of vibrating motion in which the acceleration produced due to elastic restoring force (Fr) and it is directly proportional to the negative of the displacement (X) which is produced due to external force (Fext) and always directed towards the mean position
Conditions for S.H.M
     1)      The system must have restoring force.
     2)      The system must have inertia (m).
     3)      The plane over which attached to spring moving must be frictionless  
               and at the point of spring and firm support.  
Characteristics or feature of S.H.M
             Any system executing S.H.M have the following main characters or Features.
1)     At extreme position the P.E is maximum. Because displacement (X) is
         Maximum and K.E is zero. Because velocity is zero.
2)     At mean position the K.E is maximum. Because velocity is maximum  
         while the P.E is zero. Because displacement(X) is zero.
3)     The acceleration always directed towards the mean position and it is  
         directed in the direction of restoring force(Fr).  
4)      Displacement and acceleration are always in opposite direction.
Pendulum
Definition
                Simple pendulum is consisting of bob (hard steel sphere), inextensible string and firm support. One end of spring attached with bob and the other end with firm support. These three components are from the system of simple pendulum.
Explanation
              If the bob is displaced through displacement (X) by an external force (Fext) from point (O) to point (B) against the gravitational field. So the work done by external force stored in the pendulum in the form of gravitational potential energy. When the applied external force release and the bob moves towards the mean position, Due to change of G.P.E into K.E the bob do not stay to point (O.) due to inertia (mass) the bob moves to other G.P.E side of the mean position at point (A) and again don't stay there. and moves to point (O) and then to point (B) and the bob repeats its movement about the mean position in the regular interval of time. The acceleration produce and it is always directed towards the mean position and directly proportional to the displacement (X) produce due to external force. Therefore the Simple Pendulum also executes S.H.M like mass attached to spring.
It is experimentally proved the time period of simple pendulum as
  T=2pl/g
Where T=time period of pendulum
L=length of the string of pendulum
g=gravitational acceleration.
Properties of waves
           Basically any types of wave exhibit (to show) four basic properties which are as follows.
            1)    Reflection
            2)    Refraction
            3)    Diffraction
            4)    Interference
Reflection
              When the transmitted waves (water waves, light waves, sound waves-------) strike any plane surface.(In the case of light waves on plane mirror)with the some angle after stricking with the plane it bounce back to the same medium from which it transmitted in this case is known as reflection.
Refraction
                       The banding of waves when it enters from one medium to another medium is known as refraction. The waves bend towards normal when it enters from rare medium into dense medium to the reduction is the speed of the waves.
Diffraction
        The bending of waves around the corners of objects or obstacles is known as Diffraction.
Interference
               When two (or more than two) waves each gives own displacement to the same particle of medium. The resultant displacement is equal to some of all the individual displacement. This phenomenon is known as Interference of waves.
Constructive interference
                    When two identical waves (same amplitude, same wave length, and same frequency) moving along the same direction propagation along the same medium. If both waves are in phase when they interact and they produce Constructive interference pattern (arrangement) and the resulting waves are with individual waves reinforce each other.
Destructive Interference
                          When two identical waves generated in same medium propagating in same direction, If waves are out of phase. When they interact they produce interference pattern. Which is destructive in nature and they cancel the effect of each other and the resultant waves is zero (The medium through which wave generated came into its undisturbed level).

Stationary Waves or Standing Waves
              When two identical waves (same amplitude, same frequency, same wave) generated in the same medium but propagating in opposite direction, If both waves are out of phase when they interact with each other. They formed standing waves or stationary waves. Both waves lock each other and form Loops. The 1st loop is known as the 1st Harmonic or Fundamental harmonic, 2nd is called 2nd harmonic and so on.
Fandamental or 1st Harmonic
The frequency (f) of the standing wave divided by number of loops