English: Huygens[1] proposed that every point to which a luminous disturbance reaches becomes a source of a spherical wave, and the sum of these secondary waves determines the form of the wave at any subsequent time. He assumed that the secondary waves traveled only in the "forward" direction and it is not explained in the theory why this is the case. He was able to provide a qualitative explanation of linear and spherical wave propagation, and to derive the laws of reflection and refraction using this principle.
black and white visualization for w> λ
an saothar seo a roinnt – an saothar seo a chóipeáil, a dháil amach, agus a tharchur
an saothar seo a athmheascadh – an saothar seo a oiriúnú
Ach amháin má leantar na coinníollacha seo a leanas:
sannadh – Ní mor creidiúint a thabhairt leis an saothar, faoi mar a shonraigh an údar nó tabharthóir an ceadúnais (ach ná húsáid modh a thugann le fios go thacaíonn sé/sí tú féin nó an úsáid a bhaineann tú as an saothar).
comhroinn araon – Má athraíonn tú nó síneann tú amach an saothar seo, ní féidir é a dháileadh ach amhaín faoin gceadúnas céanna nó ceann cosúil leis an gceann seo.