A planoconvex lens is made of glass of refractive index 1.5. The radius of curvature of its spherical surface is 40 cm. At what distance from the lens will a parallel beam of light will get focussed? Draw a neat, clear labelled ray diagram to show image formation from the lens. What will be the nature and power of a combination of two such lenses kept with their (i) plane surfaces in contact (ii) spherical surfaces in contact.