I am preparing for my science exam and here; we learnt in physics that a glass prism disperses white light into 7 constituent colours and for recombination of those 7 colours into white light we need to arrange an inverted prism such that its refracting surfaces are parallel to those of the first one. Fair and Square.
My doubt is since after emerging out from the first one; since all rays dont travel parallel to each other and hence; with distance their differences will be more significant; so; is it true that for perfect recombination we need to place the inverted prism close to the first one. So, does distance between prisms affect the process of recombination?
And what about rectangular glass slabs; I know that their parallel faces cancel out the dispersion but I think all 7 colours must have different lateral displacements and hence; the emergent ray may not be r.ecombined? Is this true?