Question

An object of height 2.5 cm is placed at a distance of 15 cm from the optical center ‘0' of a convex lens of focal length 10 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical center '0', principal focus F and height of the image on the diagram.

Answer 1

Answer:

height of object=2.5cm

u=-15cm

f=10cm

by lens formula

1/ v- 1/u= 1/f

1/ v=1/10-1/15

1/v=1/30

v=30 cm

Answer 2

Explanation:

given :

height of object =2.5cm

object distance = - 15cm[ by sign conventions ]

focal length =f= 10cm

image distance =v=?

from lens formula:

1/f= 1/v- 1/u

1/v= 1/f+1/u

=1/10 - 1/15

=3-2/30

=1/30

1/v= 1/30

v= 30cms

m= v/u= 30-/15= -2

nature of image :

object position is between F and C and image is formed beyond C

• real
• inverted
• magnified

m=hi/ho

hi= mxho= -2x2.5= -5cm