Draw ray diagrams to show the formation of a three times magnifier (i) real image (ii) virtual image of an object kept in front of a converging lens. Mark the positions of object, F, 2F, O and position of image clearly in the diagram.
An object of size 5 cm is kept at a distance of 25 cm from the optional centre of a converging lens of focal length 10cm. Calculate the distance of the image from the lens and size of the image.
i. 
ii. 
The data given is:
the object distance is, u=-25 cm.,
the focal length is, f=-10 cm.,
the height of the object, ho= 5 cm.,
we know that the lens formula is,
, where,
v is the image distance, u is the object distance and f is the focal length of the lens, here as the lens is concave so the focal length is positive (10 cm).
Calculations:
So, after substituting the data we have,
So, we get 
.
The magnification can be calculated by the formula,
,
,
,
The height of the image is 3.34 cm. and the image is real and inverted.