A boy stands at 30 cm distance in front of a mirror. He sees his direct image whose height is 1/5 of his actual height. Which mirror does he use?

Correct option is B

The correct answer is (b) Convex

Explanation:
• The boy is strictly observing an image that is both direct (erect) and highly diminished (1/5th the size).
• In standard optics, a Convex mirror is the only spherical mirror that consistently produces virtual, erect, and definitively diminished images regardless of the object's specific distance.

Information Booster:
• Because convex mirrors dramatically widen the field of view while shrinking the image, they are strictly used as rear-view mirrors in vehicles and security mirrors in stores.
• The magnification (m) formula is $m = -v/u$. Here, m is strictly positive (+1/5) because the image is direct/erect, which points purely to a convex mirror given the diminished scale.

Additional Knowledge:
Flat (Option a)
• A flat (plane) mirror strictly forms a virtual, erect image that is exactly the same size as the object (magnification = 1).
Concave (Option c)
• A concave mirror only forms a direct (virtual, erect) image when the object is extraordinarily close (inside the focal length), but that specific image is heavily magnified, not diminished.
Plano-concave (Option d)
• This is completely a term for optical lenses, not mirrors.
None of the above/More than one of the above (Option e)
• Incorrect, as a convex mirror handles this exact scenario.

So the correct answer is (b)