Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other, whatever may be angle of incidence. Show the same with the help of diagram.
When two plane mirrors are at right angles to each other, incident ray and
reflected ray will always be parallel to each other, whatever may be the angle
of incidence. Let us use following figure to understand this.
ED and DC are two plane mirrors placed at right angles to each other. An is
incident ray on CD and MN is normal at point of incidence. NQ is reflected ray
from N and is incident
on point Q.
QB is reflected ray and PQ is normal to ED.
∟ ANM =∟ MNQ
(angle i=angle r)
Since corresponding angles are equal
Hence, BQ ‖ AN proved
This means that incident ray and reflected ray will always be parallel;
irrespective of
value of angle of incidence
