Question

An object 5 cm high is held 25 cm away from a converging lens of focal length 10 cm.

(i) Draw the ray diagram and

(ii) Calculate the position and size of the image formed.

(iii) What is the nature of the image?

Answer 1

(i) `1/f=1/v-1/u=>1/v=1/f+1/u=>v=(uxxf)/(u+f);f=10 "cm",u=-25"cm"`

(ii) `v=((-25)xx10)/(10-25)=16.67`cm

`m=-v/u=-h_i/h_a`

`=>h_i=(vxxh_a)/u=(6.67xx5)/((-25))=-3.34`cm

(iii) Negative sign indicates that the image is real & inverted.