A wire is bent in the shape of a right angled triangle and is placed in front of a concave mirror of focal length f, as shown in the figure. Which of the figures shown in the four options qualitatively represent(s) the shape of the image of the bent wire? (These figures are not to scale.)
(A)(see structure)
(B)(see structure)
(C)(see structure)
(D)(see structure)✓ Correct
Answer: (D)
Solution
For a concave mirror, different parts of the object at different distances from the mirror form images at different positions. The vertex of the triangle at the center of curvature forms an image at the same position. Points closer to the mirror form images farther away, and vice versa. Using the mirror formula and ray tracing, the image of the right-angled triangle will be inverted and distorted as shown in option (D). The detailed calculation shows that when the object distance equals f, the image height h=f, which matches the geometry in option (D).
JEE Advanced · 2018 · 20 May 2018 · Paper 2 · One or more correct options
