Question

Draw a neat two ray diagram for the formation of images in two plane mirrors, when mirrors are at right angles to each other.

Answer 1

When two mirrors are inclined at right angles
‘O’ is an object placed in between two mirrors XY and
XZ, inclined at an angle of 90°. (See the following figure)

Taking normal incidence, I₁ and I₂ are the images formed in the plane mirror XY and XZ respectively as far behind the mirrors, as point ‘O’ is in front of them.
However, image I₁ acts as a virtual object for image mirror XZ₁ and forms an image I₃. Similarly, image I₂ acts as a virtual object for the image mirror XY₁ and forms the image I₄. The images I₃ and I₄ overlap to form a very bright image. Thus, on the whole three images are seen. In order to draw two-ray diagrams, from the position FE of the eye, draw two rays meeting at I₃,I₄ such that these ray intersect the mirror XZ at D and C.
Now draw two rays from point I₁ to join C and D intersecting mirror XY at A and B. Join O with A and B.
Similarly, in order to show image I₂, draw two rays from I₂ to the position of eye FE, such that they intersect at H and G Join H and G to ‘O’ so as to form an incident beam.