Question

a point object is placed at a distance of 30 cm from a convex mirror of focal length 30 cm the image will form at a.Infinity b.Ball C.focus D.15 CM behind the mirror

Answer 1

infinity ( ray diagram case 5)

Answer 2

Given that, a point object is placed at a distance of 30 cm from a convex mirror of focal length = f = 30 cm.
We have to calculate the distance of the image formed.
Since, we know,
Image distance = f / 2 , behind the mirror
So, 
Image distance = 30 / 2
Image distance = 15 cm , behind the mirror
Hence, option (D) is correct.
Hopefully it helps. Thanks