Question

A real inverted and diminished image is formed by a convex lens when the object is
(A) beyond 2 F but not at infinity
(B) between F and 2F
(C) at 2F
(D) at F

Answer 1

Hint: When the object is placed at 2F, the image is real, inverted and of the same size. If the object is moved away from here i.e. beyond 2F, the image moves closer to the lens i.e. between F and 2F. When the object moves farther away and reaches infinity, the image reaches the point F. IIn general, whenever the image is closer to the lens than the object, its size will be lesser than that of the object.

Complete step by step solution:
Option A : When the object is kept beyond 2F, the image forms on the other side of the lens between F and 2F. In such a case, the image is real, inverted and diminished.

Option B : When the object is kept between F and 2F, the image forms on the other side of the lens beyond 2F. In such a case, the image is real, inverted and enlarged.

Option C : When the object is kept at 2F, the image forms on the other side of the lens at 2F. In such a case, the image is real , inverted and the same size.

Option D : When the object is kept at F, the rays after refraction become parallel to each other. In such a case, the image is said to form at infinity. The size of the image is enlarged.

Therefore, the correct answer to the question is option : A

Note: Before attempting to solve the problem, the student needs to be able to understand the image formation by a convex lens for different positions of the object. The image formation knowledge also helps in option elimination in numerical questions.