相消\相長干涉

Wave interference concerns with the waves themselves, not the sources. It is therefore not necessary for the waves to come from the same source.

The conditions for constructive and destructive interference are that the two waves must be coherent (同步) and monochromatic (i.e. of the same single freuqency (單一頻率)).

如果我冇理解錯你個問題, 應該係問兩個源頭唔頭既waves之間發生相消\相長.

兩個waves可以不同波源, 試想像你手握一粒波子, 掉入一盤靜止的水入面, 咁就會做成一個個圈形既wave; 再想像手上有兩粒波子, 分別同時掉入一盤靜止的水入面, 應該會發生兩個圈形既wave, 但係兩個wave交疊的地方就會發上相消/相長.

think bigger, 兩粒波子變成兩個保齡球, 兩個保齡球掉入靜止的泳池水入面, 喺波池入面放好多乒乓波, 你可以想像到個waves會令d乒乓波浮下浮下, 同只有一個保齡球掉落既時候比較, 乒乓浮動的幅度大左, 呢個就係相長(兩個waves加埋令到個乒乓波浮上浮落既幅度大左, 所以係相長), 相反, 個乒乓波唔郁, 即係相消.

再想像將其中一個保齡球換成鉛球, 兩個waves變得唔一樣, 不過, 一樣可以有相消相長.

如果有圖可能會解釋得好d...