Question

Q17. If the image formed by a lens for all positions of an object placed in front of it is
always erect and diminished, what is the nature of this lens ? Draw a ray diagram
to justify your answer. If the numerical value of the power of this lens is 10 D. what
is its focal length in the Cartesian system?​

Answer 1

Answer:

The lens in a concave lens.

Explanation:

It always creates a virtual and erect image that forms in the left side of the lens.The image is either diminished or highly diminished.

See the attachment for the ray diagrams.....

Power = 10 D

We know,

P=1/f(in meters)

then,  10=1/f

or     f=0.1 m

or   -0.1 m

or    -10 cm