The refracting angle of prism is 14110 and refractive index is 1.5. A thin convex lens of focal length 20 cm is placed at distance 30 cm from the point source S as shown in figure. The position of image of point source S is

∵δ=(μ−1)A=(1.5−1)1411×π180=12×1411×227×180=190 ∴tanδ=δ=h15 ⇒190=h15 ∴h=16cm S’ behaves as object for the thin convex lens. For the lens,u=−30cm,f=+20cm∴1v−1u=1f ∵1v−1−30=120 Or 1v=120−130=3−260 ∴v=60 cm ∴h'=−2×16=−13cm     [∵h'h=vu]