Deduce the equivalent focal length of two convex lenses of focal lengths `F_(1) and F_(2)` when placed in contact.

Arrange the following combinations in the increasing order of focal length Two piano convex lenses of focal lengths 15 cm and 30 cm in contact Two convex lens of focal lengths 40 cm and 50 cm in contact Two convex lenses of focal length 20 cm separated by 5 cm

Arrange the following combinations in the increasing order of focal length a) Two piano convex lenses of focal lengths 20 cm and 30 cm in contact b) Two convex lens of focal lengths 20 cm and 10 cm in contact Two convex lenses of focal length 25 cm separated by 5 cm.

A convex lens of focal length 40 cm a concave lens of focal length 40 and a concave lens of focal length 15 cm are placed in contact. The power of this combination of are placed in contact. The power of this combination in diopters is

We combined a convex lens of focal length f_(1) and concave lens of focal lengths f_(2) and their combined focal length was F . The combination of these lenses will behave like a concave lens, if

A convex lens of focal length A and a concave lens of focal length B are placed in contact. The focal length of the combination is

A convex lens of focal length x and a concave lens of focal length y are placed in contact. The focal length of the combination is

Derive the relation : (1)/(F) =(1)/(f_(1)) +(1)/(f_(2)) ,where f_(1) and f_(2) are focal length of two thin lenses and F is the focal length of the combination in contact.

(a) Using the ray diagram for a system of two lenses of focal lengths f_(1) and f_(2) in contact with each other, show that the two lens system can be regarded as equivalent to a single lens of focal length f, where (1)/(f)=(1)/(f_(1))+(1)/(f_(2)) Also write the relation for the equivalent power of the lens combination. (b) Determine the position of the image formed by the lens combination given in the figure.

In Fig., there are two convex lenses L_(1) and L_(2) having focal lengths F_(1) and F_(2) respectively. The distance between L_(1) and L_(2) will be :