Problem 10.1. An object 4 cm tall is placed near the axis of a thin converging lens. If the focal length of the lens is 25 cm, where will the image be formed and what will be the size of the image? Sketch the principal ray diagram. Geometrical Optics problem 1. Sindh Textbook Board (stb) problems

Problem 10.1. An object 4 cm tall is placed near the axis of a thin converging lens. If the focal length of the lens is 25 cm, where will the image be formed and what will be the size of the image? Sketch the principal ray diagram...

Data 

Focal length f =25cm 

Size of object ho =4cm

Object distance p =33.33cm 

To fin

Image distance q=?

Size of images =?

Solution 

Using this lens formula is 1/f=1/p+ 1/q 》

1/q=1/f - 1/p =1/25 - 1/33.33cm 

1/q=33.33 _25/25×33.33 = 8.33/8.33.25=0.01 

q=1/0.001 = 100cm.    Q = 100cm Ans 

Image hight can be found by magnification  formula as

 Hį/ho=q/p

Hi= q/p ho = 100 /33.33 ×4 =12cm