Question

an object is placed at a distance of 20cm from convex lens of focal length 15cm find the image distance​

Answer 1

Image distance = 60 cm

Step-by-step explanation:

Object distance from a convex lens = 20 cm

Focal length of convex lens = 15 cm

Use the following relation between the object distance, focal length and image distance.

`(1)/(object\,\,distance)+(1)/(image\,\,distance) =(1)/(focal\,\,length)`

`(1)/(20)+(1)/(image\,\,distance)=(1)/(15)\\\\ (1)/(image\,\,distance)= (1)/(15)-(1)/(20)\\\\ (1)/(image\,\,distance)= (4-3)/(60) \\\\ (1)/(image\,\,distance)=(1)/(60)`

Therefore,

Image distance = 60 cm