Question

A 2.0cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 10 cm. the distance of object from the lens is 15 cm.what is ray diagram for this question?

Answer 1

Hi..

GIVEN,
Object distance = u= -15 cm(object are always taken as negative)
Focal length =f = -10 cm(focal length is taken as negative in the case of concave lens )

object height = ho = 2cm

USING ,1/v - 1/u =1/f

1/v = 1/f + 1/u
= -1/10 + (-1/15)
= -1/10 - 1/15
= (-3 -2)/30
=-5/30
v = -6

Therefore image must be formed 6 cm in front of mirror.Negative sign show image formed in front of lens.

Now, image height = hi

Using,m= hi/ho = v/u

hi/2 = (-6)/(-15)
hi/2= 2/5
hi = 4/5 cm

hi = 0.8 cm
Therefore the size of image is 0.8 cm above the principal axis.

m =hi/h o

m = 0.8/2

m= 1/2.5

Therefore image is vertual , erect and diminshed...


Hope this helps u!!

Answer 2

hope this helps you........