A convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis, the number of images formed are :

If in a plano-convex lens, the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm, then the refractive index of the material of lens will be

A convex lens of focal length 50 cm forms a real image of size three times of size of object then position of object will be :

A beam of light propagating in medium A with index of refraction n (A) passes across an interface into medium B with index of refraction n(B). The angle of incidence is greater than the angle of refraction ; v(A) and v(B) denote the speed of light in A and B. Then which of the following is true :