INTERFERENCE

Acutally
whether there is the CONSTRUCTIVE OR DESTRUCTIVE INTERFERENCE in that line
you should consider the PATH DIFFERENCE
In my mind , there are BOTH CONSTRUCTIVE AND DESTRUCTIVE INTERFERENCE occured in that line
as the PATH DIFFERENCE is different at any point


N line means totally destructive
A line means totally constructive
many position will not be totally con/destructive
so there maybe a bit constructive / a bit desutrctive interference occured

i am not sure about the straight line u mentioned
if it is equidistant to both sources, then there must be constructive interference occur on it
but if it is only drawn randomly between two sources, then constructive or destructive interference may occur on it

ANTINODAL line indicates points of constructive interference
NODAL line indicates points of destructive interference

there will be a smaller value of interference in those areas without them
相長干涉或建設性干涉(constructive interference)：兩波重疊時，合成波的振幅大於成分波的振幅者。若兩波剛好同相干涉，會產生最大的振幅，稱為完全相長干涉。
whenever 2 crests or 2 trough met, and produce a larger crests or trough, constructive interference occurs
相消干涉或破壞性干涉 (destructive interference)：兩波重疊時，合成波的振幅小於成分波的振幅者。若兩波剛好反相干涉，會產生最小的振幅，稱為完全相消干涉。
whenever 1 crest and 1 trough met, and produce a smaller crests or trough, destructive interference occurs

that means it is not a complete constructive or destructive interference only, interference still exist

2個source之間係constructive同destructive都有,而邊一種就要睇下佢地既
path difference,每隔住半個wavelength(如source seperation大過一個wavelength)就會出另一種interfernce

2008-06-12 18:27:10 補充：
據我記憶(我已考完alevel兩個月了),不可以說a "bit" constructive/destructive intereference,
如果一個point既path difference唔係半個/整數既wavelength,e一個point就不能說有interefernce occur as its amplitude is always changing,只可說"they superpose together"我認為a "bit" constructive/destructive intereference是個不可接受既說法