Ten identical converging thin lenses,each of focal length `10cm`are in contact .What is the power of the combined lens.

Two thin lenses of focal lenths + 10 cm and - 5 cm are kept in contact.What is the power of combination.

Two lenses of focal length 10 cm and -20 cm are placed in contact .What is the total power of the combination?

Two lenses of focal lengths -20cm and +10cm are put in contact.Find power of the combination

Two convex lenses of focal length 10 cm each are combined. What will be the focal length of the combined lens ?

Find the effective power and focal length of two lenses of focal lengths 50 cm and -200 cm when put in contact. What is the nature of the combined lens?

Two thin lenses of focal lengths 20cm and 25cm are placed in contact. The effective power of the combination is

Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact. The effective power of the combinations is

Two thin lenses of focal lengths 20 cm and 25 cm are placed in a contact. The effective power of the combination is