Two equi convex lenses each of focal lengths 20 cm and refractive index 1.5 are placed in & contact and space between them is filled with water of refractive index `4/3`. The combination works as

Two identical equiconvex lenses of refractive index 3//2 and focal length 16 cm are kept in contact. The space between the lenses is filled with water of refractive index 4//3 . What is the focal length of the combination ?

Two identical equiconvex lenses of refractive index 3/2 and focal length 16cm are kept in contact. The space between the lenses is filled with water of refractive indext 4/3 . What is the focal length of the combination?

Two equi-convex lenses, each of radius of curvature 20 cm and refractive index 1.5 are placed in contact. If water of refractive index 4/3 is placed in between the lenses, the focal length of the combination is,

Two equi-convex lenses of focal length 30cm and 70cm, made of material of refractive index =1.5, are held in contact coaxially by a rubber band round their edges.A liquidof refractive index 1.3 is introduced in the space between the lenses filling it completely. Find the position of the image of a luminous point object placed on teh axis of the combination lens at a distance of 90cm from it.

Two equi-convex lenses of focal length 30cm and 70cm, made of material of refractive index =1.5, are held in contact coaxially by a rubber band round their edges.A liquidof refractive index 1.3 is introduced in the space between the lenses filling it completely. Find the position of the image of a luminous point object placed on teh axis of the combination lens at a distance of 90cm from it.

Two equi-convex lenses of focal length 30cm and 70cm, made of material of refractive index =1.5, are held in contact coaxially by a rubber band round their edges.A liquidof refractive index 1.3 is introduced in the space between the lenses filling it completely. Find the position of the image of a luminous point object placed on teh axis of the combination lens at a distance of 90cm from it.