Physics

• Pulse 


  A single disturbance in a medium
• Transverse pulse

   a pulse in which the particles of the medium move at right angles to the direction of motion of the pulse 
• Amplitude 

   the maximum disturbance of a particle from its rest position
• Transverse wave 

   a wave in which the particles of the medium vibrate at right angles to the direction of motion of the wave . A transverse wave is a succession of pulses 
• Crest 

  highest position on a wave
• Trough 

   lowest position on a wave 
• Principle of superposition

   the algebraic sum of the amplitudes of two pulses that occupy the same space at the same time 
• Constructive interference 

   the phenomenon where the crest of one pulse overlaps with the crest of another to provide a pulse of increased amplitude 
•  Destructive interference

   the phenomenon where the crest of one pulse overlaps with the trough of another resulting in a pulse of decreased amplitude 
• Wavelength

  the distance between two successive points in phase 
• In phase 

   two points in phase are separated by a whole number multiple of complete wavelengths
• Out of phase

   points that are not separated by a while number multiple of complete wavelengths
• Frequency

  the number of wave pulses per second
• Period

   the time taken for one complete wave pulse 
• Wave speed

  the distance travelled by a point on a wave per unit time 
• Longitudinal waves

   a wave in which the particles of the medium vibrate parallel to the direction of motion of the wave
• Compression

   a region of high pressure in a longitudinal wave 
• Rarefaction

   a region of low pressure in a longitudinal wave
• Sound waves

  created by vibrations in the medium n the direction of propagation . The vibrations cause a regular variation in pressure in the medium
• Echo

  a reflection of sound waves
• Imaging

  when a wave encounters a boundary between two media , part of the wave is reflected , part is absorbed , part is transmitted
• Propagation

   when an electric field oscillating in one plane uses a magnetic field oscillating in a plane at right angles to it , which produces an oscillating field and so on
• Neutrally charged 

  Equal number of protons and electrons 
• Positively charged 

  Deficiency of electrons 
• Negatively charged 

  Excess amount of electrons 
• Turbo-electric charging 

  A type of contact electrification in which certain metals become electrically charged after they come into contact with different materials and are then deprecated 
• Principle of conservation of charge 

  The net charge of an isolated system remains constant during any physical process 
• Principle of charge Quantisation

  All charges in the universe consist of an integer multiple of the charge on one electron 
• Electrostatic force is attractive if opposite signs, repulsive if same sign