focal length of the convex lens is 20 cm and the identification reduced to 1 by 3 find the distance of the object from the optical centre
Answers
Answered by
0
Answer:
18 cm is good answer. also
Answered by
1
hi mate,
Solution: object distance from the optical centre of the lens is 80cm.
explanation : focal length of convex lens , f = +20cm
a/c to question,
size of image = 1/3 × size of object.
so, magnification , m = -1/3
we know, magnification of lens , m = v/u
so, v/u = -1/3
so, v = -u/3 ........(1)
now applying lens maker formula,
1/v - 1/u = 1/f
or, 1/(-u/3) - 1/u = 1/20
or, -3/u - 1/u = 1/20
or, u = -80 cm
hence, object is placed 80cm from the pole of convex lens.
i hope it helps you.
Similar questions