Two convex lenses of focal length 10 cm each are placed in contact. What is the focal length of the combination?

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

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

Two lenses of power 15.5 D and -5.5 D are placed in contact.What is teh focal length of the combbination?

A convex lens of focal lenth 30 cm and a concave lens of focal length 60 cm are placed in contact.Find the power of the combination.

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

A convex lens of foal length 30 cm and a concave lens of focal length 60 cm are placed in contact.If the object is placed 40 cm away from the combination ,, find the position of the image.

Two thin lenses of focal length f_1 and f_2 are placed in contant .The focal length of the composite lens will be

Two thin lenses of pwer +5D and -3D are in contact. What is the focal length of the combnation?

A converging and a diverging lens of equal focal lengths are placed co-axially in contact. Find the power and the focal length of the combination.