Question

WAVE INTERFERENCE: Discuss interference, constructive and destructive interference. List the phase and path difference equations for constructive and destructive conditions. Discuss the phase changes condition due to reflection of light from a surface. Summarize equations of interference for thin film. Give real life examples for interference

Answer 1

t is phenomenon - redistribution interference of light of light energy in the medium on the account of two Cho coherent sources. Construtive interference - When crest of one wave fall on Crest on another Wave then amplitude and Indensity at that point is maximum and this is known Instructive interference as Let y = = a sinut a sinut and y = b sinkut td) superimpose at angle phase difference d. Now y = y, ty a sinut + b sin(Wtto) = asinut t b sin Wt Casa b sin wt Casa + b Gesult sind Y = sinut (a + besod) + Casut (bsind) Put (arb ssd ) = Reso b sind R sino Y = R Sin wt aso + RCSwt sino = R Sin (wt to)

Y= R sin (wtto) Resultant wave, with Ramplitude Resultant Ware intensity - R² = R² - Asintotto) R² (6530 + sinho) a3 +6² 632d + 2ab es d + b² sind Labes of R = a² +6² +2ab Hence For constructive interference R should be maximum cosd should be maximum Where n=0, 1, 2, 3 d = ant Path difference x-14 = xanIT 21 20 / x = nh Where n=0,1,2 Distructive interference - When creast of one wave fall on trough of other wave them amplitude and intensity decreases. This is known as distructive interference, Condition for distructive interference - cosd should be minimum d - T, 31,51 (2n-1) T where n = 1, 2, 3, 4- -

Path difference X= (2n-1) ITXA = 2 TT Il (2n-1) a Where n = 1, 2, 3 2 reflected by Real life examples light this oil film floating by this soap bo bubbles. on water, light reflected Reflected 180° light experience incident light. phase change to Phase change is 180" after reflection, interference due to this film here d = 180°, then you can solve equation,