Question

with the help of the ray diagram illustrate the change in position, nature and size of the image formed if they convex lens is replaced by a concave lens of same focal length. when the object is placed at 2F​

Answer 1

GiveN :-

• A convex lens is replaced by concave lens when the object is at 2F .

To FinD :-

• The change in position , nature and size of the image .

AnsweR :-

Here we have two cases of different lens when the object is placed at 2F . Firstly the object is infront of a convex lens and secondly it's infront of a concave lens . For the ray diagram refer to the attachment.

$\underline{\color{purple}{\textsf{\textbf{ Case 1 :- } Object in front of convex lens }}}$

For ray digram refer to first attachment.

When we keep an object at 2f then an image of equal size is obtained on the the focal length on the other side of the lens. The image formed is real and inverted .

• Nature - Real and inverted .

• Size - The size of the image is equal to the size of the object .

$\rule{200}2$

$\underline{\color{purple}{\textsf{\textbf{ Case 1 :- } Object in front of concave lens }}}$

For ray digram refer to the second attachment.

When we keep a object in front of a concave lens at any Position here 2F , then a diminished image is formed between Focus and Optical centre. The image formed is virtual and erect .

• Nature - Virtual and erect .

• Size - The size of the image is smaller than the size of the object .

$\rule{200}2$

$\underline{\color{purple}{\textsf{\textbf{ Final Conclusion :- } }}}$

So , when we change the lens when the object is at 2F then , a smaller image is formed as compared to the first case. Also the nature of the image also changes that is from real and erect in first case to virtual and erect in second case .