In order to obtain a magnification of, `-0.75` with a convex lens of focal length 8 cm, the object should be placed:

To obtain a magnification of -2 with a convex lens of focal length 10 cm, the object should be placed:

In order to obtain a real image twice the size of the with a convex lens of focal length 15 cm, the object distance should be:

To obtain a magnification of, -0.5 with a convex lens, the object should be placed:

In order to obtain a magnification of, -3 (minus 3) with a convex lens, the object should be placed.

In order to obtain a real image of magnification 2 using a convergin lens of focal length 20 cm,where should an object be placed?

The focal length of the objective of a telescope is 60 cm. To obtain a magnification of 20, the focal length of the eye-piece should be :