A convex lens is made of a material having refractive index 1.2. Both the surfaces of the lens are convex. If it is dipped into water (μ = 1.33), it will behave like

Two concave lenses L₁ and L₂ are kept in contact with each other. If the space between the two lenses is filled with a material of smaller refractive index, the magnitude of the focal length of the combination

A thin lens is made with a material having refractive index μ = 1.5. Both the surfaces of the lens are convex. It is dipped in water (μ = 1.33). It will behave like

A point object O is placed on the principal axis of a convex lens of focal length f= 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. An eye is placed 60 cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is

The rays of different colours fail to converge at a point after going through a converging lens. This defect is called