Question

An erect image 2cm high is formed 12 cm from the lens whose power is 25/3 D. If the Object is 3cm high, calculate the distance of the object from its image.

Answer 1

Answer:

Focal length of the lens is 4 cm.

Explanation:

It is given that,

Height of image, h' = 2 cm

Image distance, v = -12 cm

Height of object, h = 0.5 cm  

We have to find the focal length of the lens. It is a convex lens because the image is large as compared to object. Firstly calculating magnification of lens as :

Explanation: