What is the nature of the image formed by a convex lens if the magnification produced by the lens is, - 0.5?

Write down the magnification formula for a lens in terms of object distance and image distance. How does this magnification formula for a lens differ from the corresponding formula for a mirror?

What is the nature of the image formed by a convex lens if the magnification produced by the lens is +3?

What is the position of image when an object is placed at a distance of 12 cm from a convex lens of focal length 12 cm?

Describe the nature of image formed when an object is placed at a distance of 30 cm from a convex lens of focal length 15 cm.