▁the ▁super position ▁principle ▁holds ▁( which ▁is ▁often ▁but ▁not ▁always ; ▁see ▁non linear ▁opt ics ), ▁the ▁behavior ▁of ▁any ▁light ▁wave ▁can ▁be ▁understood ▁as ▁a ▁super position ▁of ▁the ▁behavior ▁of ▁these ▁simpler ▁plane ▁waves . ▁ ▁W ave ▁super position ▁ ▁W aves ▁are ▁usually ▁described ▁by ▁variations ▁in ▁some ▁parameter ▁through ▁space ▁and ▁time — for ▁example , ▁height ▁in ▁a ▁water ▁wave , ▁pressure ▁in ▁a ▁sound ▁wave , ▁or ▁the ▁elect romagnet ic ▁field ▁in ▁a ▁light ▁wave . ▁The ▁value ▁of ▁this ▁parameter ▁is ▁called ▁the ▁amplitude ▁of ▁the ▁wave , ▁and ▁the ▁wave ▁itself ▁is ▁a ▁function ▁specifying ▁the ▁amplitude ▁at ▁each ▁point . ▁ ▁In ▁any ▁system ▁with ▁waves , ▁the ▁wave form ▁at ▁a ▁given ▁time ▁is ▁a ▁function ▁of ▁the ▁sources ▁( i . e ., ▁external ▁forces , ▁if ▁any , ▁that ▁create ▁or ▁affect ▁the ▁wave ) ▁and ▁initial ▁conditions ▁of ▁the ▁system . ▁In ▁many ▁cases ▁( for ▁example , ▁in ▁the ▁classic ▁wave ▁equation ), ▁the ▁equation ▁describing ▁the ▁wave ▁is ▁linear . ▁When ▁this ▁is ▁true , ▁the ▁super position ▁principle ▁can ▁be ▁applied . ▁That ▁means ▁that ▁the ▁net ▁amplitude ▁caused ▁by ▁two ▁or ▁more ▁waves ▁travers ing ▁the ▁same ▁space ▁is ▁the ▁sum ▁of ▁the ▁amplit udes ▁that ▁would ▁have ▁been ▁produced ▁by ▁the ▁individual ▁waves ▁separately . ▁For ▁example , ▁two ▁waves ▁travel ing ▁towards ▁each ▁other ▁will ▁pass ▁right ▁through ▁each ▁other ▁without ▁any ▁dist ort ion ▁on ▁the ▁other