Question

The Image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens . If the image is three times the size of the flame and the distance between the lens and the image is 80 Cm at what distance should the candle be placed from the lens ? what is the nature of the image at a distance of 80 cm and the lens ?​

Answer 1

Explanation:

Magnification is 3 times and image distance v=80cm

Magnification =  

u

v

​  

 

Or,3=  

u

80cm

​  

 

Or, u=  

3

80cm

​  

 

since,object distance is taken as negative; as per sign convention so,

or, u=−  

3

80cm

​  

 

Nature of image: since image is formed on the other side of lens hence it is a real image and inverted image.

Nature of Lens: Enlarged image is formed by convex lens and not by concave lens, so it is a convex lens.