Two thin lenses of power +4 D and -2 D are in contact. What is the focal length of the combination ?
Two thin lenses of power +5 D and -2.5 D are in contact. What is the focal length of the combination ?
Two thin lenses of power + 5D and - 3D are in contact. What is the focal length of the combination ?
Two thin lenses of power + 3 D and - 1 D are held in contact with each other. Focal length of the combination is :
Two lenses of powers -1.5 D and +2.75D are kept in contact. Find the focal length of the combination.
Two lenses of power 15D and -3D are placed in contact. The focal length of the combination is a
Two lenses of power + 15 D and - 5 D are in contact with each other. What is the focal length of the combination ? What would be the position of image formed by the combination for an object at 30 cm ?
Two lens of power + 15 D and - 5 D are in contact with each other. What is the focal length of the combination ? What would be the position of image formed by the combination for an object at 30 cm ?