(a) Draw a ray di

(a)

When an object is placed any-where between infinite and optical center of a concave lens, the image formed is

(i) Between O and F.

(ii) Virtual, erect.

(iii) Diminished.

(b) CB = - u

CF = - f

CB' = - v

The relation between u, v and f is given by the lens formula:

As both u and v are negative the above equation will change to

We know that the focal length of a concave lens is negative, so the above equation will be changed to,

(c) Magnification m = -1

v = +40 cm (real and inverted)

Nature of the lens = ?

Power of the lens, P = ?

According to the lens formula,

Thus, focal length = 20 cm

Because the focal length is positive, thus it is convex lens.

Since power of lens is positive, lens will be converging in nature.