Question

AB is an object and A'B' is its image. Then, match the following with the object distance. f: focal length.

• A. $|u|=2f$
• B. $|u|>2f$
• C. $|u|<f$

Answer 1

1)

⇒Since image height = object height,
⇒So object must be kept at $2F_1$.

2)

⇒Since image height < object height so
⇒The object must be kept beyond $2F_1$

3)

⇒ Since image and object is at same side. So, the only possibility is object kept between focus and optical centre.

4)
⇒Since image height > object height and image is inverted.
⇒So, object must be kept between $2F_1$ and $F_1$.