Q1. A pen is placed between two plane mirrors which are at right angles to each other. The number of images formed of the pen is:
A 4
B 2
C 3 Correct
D 5
Explanation
For two plane mirrors inclined at an angle θ, when 360/θ is an integer, the number of images is (360/θ) - 1. Here the mirrors are at right angles, so θ = 90°. Thus 360/90 = 4 and the number of images is 4 - 1 = 3. Two is what each mirror might suggest separately, but multiple reflection adds another image. Four would include the object itself, which is not counted as an image. Five has no basis for this angle.