Question

what is power of lens determine the nature and power of a lens whose focal length is - 20 cm. The image of the an object formed by a lens is real inverted and of the same size as the object if the image is a distance of 50cm from the object determine the nature and power of the lens draw a labelled ray diagram to show the image formation in this case​

Answer 1

Here the Focal length is -20.

therefore the lens is concave.

Here power = 1/20 cm

=> p=1/0.2m

=>5 D