NDA General Ability Question (2026) — Solution

Step-by-step solution

For a spherical mirror, the mirror formula is given by 1 v + 1 u = 1 f . For a real object placed in front of the mirror, the object distance u is negative. Let u = -x where x > 0. For a convex mirror, the focal length f is positive. Substituting u into the mirror formula gives: 1 v - 1 x = 1 f 1 v = 1 f + 1 x Since both f and x are positive, 1 v > 1 f . This implies that 0 Thus, the image distance v is always positive and less than the focal length f. The image is always formed behind the mirror, between the pole and the principal focus, irrespective of the object's position. A plane mirror forms an image at the same distance as the object, and a concave mirror can form images beyond the focus or even at infinity depending on the object distance. Answer: It is a convex mirror.