SOUND

• SOUND IS A MECHANICAL WAVE - WHY?


  SOUNDS NEEDS A MEDIUM WITH PARTICLES TO TRAVEL
• SOUND NEEDS A MEDIUM FOR PROPAGATION
• SOUND CANNOT TRAVEL THROUGH VACCUM - WHY?


  THERE ARE NO PARTICLES IN SPACE , IT DOES NOT HAVE A MEDIUM TO PROPAGATE
• TYPES OF WAVE - TRANSVERSE , LONGITUDINAL
• SOUND IS A FORM OF ENERGY WHICH PRODUCES A SENSATION OF HEARING IN OUR EAR
• SOUND IS PRODUCED THROUGH VIBRATIONS
• SOURCE(WHERE SOUND IS PRODUCED)-MEDIUM(THE PATH THE SOUND TRAVELS) - RECEIVER(WHERE SOUND IS HEARD)
• HIGH DENSITY - COMPRESSION
• LOW DENSITY - RAREFACTIONS
• SOUND IS PROPAGATED THROUGH A MEDIUM WITH THE HELP OF A WAVE CREATED THROUGH PARTICLES HAVING HIGH DENSITY REGIONS CALLED COMPRESSION AND LOW DENSITY REGIONS CALLED RAREFRACTIONS .
• WHAT IS TRANSVERSE WAVE ?

  WHEN THE PARTICLES OF THE MEDIUM VIBRATE PERPENDICULAR IN THE DIRECTION OF WAVE
• WHAT IS LONGITUDINAL WAVE ?


  WHEN THE PARTICLES OF THE MEDIUM VIBRATE PARALLELY IN THE DIRECTION OF WAVE
• WHERE THE DENSITY OF AIR IS HIGH , PRESSURE IS HIGH AS WELL.
• SOUND TRAVELS THROUGH AIR , WATER, SOLIDS
• NO MEDIUM = NO SOUND
• GAS - FAST

  WATER - FASTER

  SOLIDS - FASTEST
• SOUND PROPAGATES THROUGH PARTICLES
• AS THE PARTICLES IN SOLID ARE VERY CLOSELY PACKED , THE SPEED OF SOUND PROPAGATES FASTEST
• PEAKS ARE KNOWN AS CREST

  THE POINT WITH THE HIGHEST AMPLITUDE IS KNOWN AS CREST .
• LOW POINTS ARE KNOWN AS TROUGHS

  THE POINT WITH THE LOWEST AMPLITUDE IS KNOWN AS TROUGH .
• MEAN POSITION - 0
• THE DISTANCE BETWEEN ONE PEAK AND ANOTHER IS WAVELENGTH
• WAVE LENGTH- The distance between the trough and the crest of a wave.

  DENOTED BY LAMBDA
• THE TIME TAKEN BY ONE WAVE - TIME PERIOD
• FREQUENCY - The number of waves that passes per second is known as frequency.
• FREQUENCY = (1/time period)

  SI UNIT - HERTZ (Hz)
• AMPLITUDE - It is the maximum displacement from mean position to peak or trough. Denoted by A
• LOUDNESS IS A PRODUCT OF THE AMOUNT OF SOUND WAVES.
• AMPLITUDE IS AN OBJECTIVE PROPERTY

  LOUDNESS IS A SUBJECTIVE PROPERTY
• LOUDNESS IS DIRECTLY PROPORTIONAL TO SQUARE OF THE AMPLITUDE
• LOW PITCH SOUND - LOW FREQUENCY OF VIBRATION
• SHRILL/ HIGH PITCH SOUND - HIGH FREQUENCY OF VIBRATION
• TONE - SOUND OF SINGLE FREQUENCY IS CALLED TONE
• TIMBRE - THE QUALITY OF WAVE
• WHEN THE SOUND CROSSES 80 dB , WE CALL IT NOISE
• SONIC SOUND - THE AUDIBLE RANGE OF SOUND FOR HUMAN BEINGS EXTENDS FROM ABOUT 20Hz TO 20000Hz
• INFRA SOUND - Animals can hear below 20 Hz
• ULTRA SOUND - SOUND OVER 20,000Hz
• ECHO = S=2d/t
• SPEED OF SOUND IN AIR = 344m/s