引用:
原帖由 yeungwk91 於 2016-3-13 11:24 PM 發表
I dont know what u mean by "imply.
Coherent sources are sources which are "in phase". such that their motion is always in the same direction.
and then
path diff. = n wavelength => constructiv ...
Coherent sources do not necessarily mean they are in phase. As long as the two wave sources have constant phase difference, they are said to be coherent. In HKDSE, the two sources can be either in phase or anti-phase. Students are expected to know how to convert between path difference and phase difference for both bases.
In order to have an observable interference pattern, the interfering waves must be coherent, i.e. they must have constant phase difference.