An object of size 3.0cm is placed 14cm in front of a concave lens of focal length 21cm. Describe the image produced by the lens. What happens if the object is moved further away from the lens?

Explanation

`v = 8.4 cm`, image is erect and virtual. It is diminished to a size 1.8cm. As `urarroo, v rarrf` (but never beyond f while `m rarr 0`).
Note that when the object is placed at the focus of the concave lens (21cm), the image is located at 10.5 cm (not at infinity as one might wrongly think).