The magnification of an image formed by a lens is- 1. If the distance of the image from the optical centre of the lens is 35 cm, where is the object placed? What is the nature and focal length of the lens? If the object is displaced 20 cm towards the optical centre of the lens, where would the image be formed and what will be its nature? Draw a ray diagram to justify your answer.
Given,
Magnification= -1
Image distance v= 35 cm i.e. image formed behind the mirror so it is real.
Object distance u =??
Focal length =??
Height of image = - height of object
This means that the size of image is of same size as object but the image is inverted.
So it is a convex lens.
Also,
Object distance = -35 cm
Object is placed 35 cm left to the mirror i.e.
u = 35 cm
We know that lens formula is:
Substituting the values given:
f = 17.5 cm
If object distance is displaced 20 cm towards the optical centre of the convex lens then
Object distance =35-20 cm
= 15 cm
i.e. object is placed between pole and focus of convex lens
Image formed in this case will be:
● On same side of object
● Enlarged
● Virtual and erect