Question

State the changes in the position, size and nature of the image when the object is brought from infinity up to the convex lens. Illustrate your answer by drawing ray diagrams.

Answer 1

(i) When the object is situated at infinity, the position of image is at F₂, it is very much diminished in size and it is real and inverted. 

(ii) When the object (AB) is situated beyond 2F₁, the position of image (A'B') is between F₂ and 2F₂, it is diminished in size and real and inverted.

(iii) When the object (AB) is situated at 2F₁, the position of image (A'B') is at 2F₂, it is of same size as the object and real and inverted.

(iv) When the object (AB) is situated between 2F₁ and F₁, the position of image (A'B') is beyond 2F₂, it is magnified in size and real and inverted.

(v) When the object (AB) is situated at F₁, the position of image is at infinity; it is very much magnified in size and real and inverted.

(vi) When the object (AB) is situated between lens and F₁, the position of image (CD) is on the same side, behind the object; it is magnified in size and virtual and upright.