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

Answer

The Size of the object h1=3cm

An Object distance u=-14cm

The Focal length of the concave lens f=- 21cm

Image distance=v

As-per to the lens formula, we have the relation:

Therefore the image is formed on the other side of the lens 8.4cm away as of it. The negative sign demonstrate that the image is erect and virtual.

The magnification of a image is given as

Therefore the height of the image is 1.8cm

If an object is moved further away from the lens then the virtual image will move toward the focus of the lens but not beyond it. The size of the image will reduce with the increase in the object distance.