Q.

The position of the image formed by the combination of lenses is                    [2024]

1 30 cm (left of third lens)  
2 15 cm (right of second lens)  
3 15 cm (left of second lens)  
4 30 cm (right of third lens)  

Ans.

(4)

Here we will use the lens formula three times, for lens 1

u=-30 cm,  f=10 cm

1v-1u=1f1v1-1-30=110v1=15 cm

For 2nd lens u=10 cm,  f=-10 cm

v2

For 3rd lens: f=30 cm,  u=-,  v=?

So v will be 30 cm.