A split lens has two parts separated by 4 cm and focal length is f. An object is placed at a distance 3f/2 from C as shown in figure. The distance between the images formed by the two halves (in cm) is.

 

For upper part of lens, $u=-\frac{3f}{2},h_0=2cm$

$m=\frac{h_i}{h_0}=\frac{f}{f+\left(\frac{-3f}{2}\right)}=2$

$h_i=2\times 2=4 cm$

i.e image is formed at a height of 6 cm (i.e 2+4) from main principal axis. (above principal axis) 

Similarly, for lower part, image is formed 6 cm below main principal axis. Hence distance between image = 6 + 6 = 12 cm.