Question

an object 2cm tall is place on the axis of a convex lens of focal length 5cm at a distance of 10m from the optical center of the lens find the the nature position and size of the image formed.

Answer 1

Standard thin lens equation will be used  

1/f = 1/u + 1/v 

F = 5cm 

U = 10m  = 1000cm 

So 1/v = 1/f - 1/u 

1/v = 1/5 - 1/1000 

Or v = 5.025cm  ( the image distance) 

The formula for magnification is 

M = hi/ho = -v/u 

Where hi is the height of the image and ho is the height of the object (=2cm) 

Or hi = -vho/u 

Or hi = - (5.025x2) / 1000 

Or the height of the image is   

Hi = 0.01005cm 

From the above resutls we can conculde this that  

The image is inverted ( hi is negative) Its highly diminished ( hi is smaller than ho) It is the virtual (v is positive)