Light

Light is a Wave-Like Disturbance                                                             Constructive Interference                                                         Waves from two sources start out in phase. Constructive interferenceoccurs if:      d2 - d1 =  n       n = 0, 1, 2, 3, .....----------------------------------Difference must be an integer number ofwavelengths         Destructive Interference                                                                                          Waves from two sources start out in phase. Destructive interferenceoccurs if:d2 - d1 =  (2n + 1) /2)       n = 0, 1, 2, 3, ....----------------------------------Difference must be an odd half-integer number of wavelengths.            Interference of Waves from Two Sources                                              In some places the water wavefronts are in phase (bright spots). In other places the fronts overlap with peak and valley and interfere destructively (darker spots).                              Young's Double Slit Experiment                                                   Young's Double Slit           Thomas Young  (1801)                    Constructive Inteference                                                                                         For a bright band at P:      = d sin      or   = d sin      or   = d sin          etc For a given  , bright bands occur at sin  =      0                       =    /d                     =  2 /d                      =  3 /d d sin  = m ,       m = 0, 1, 2, ....