The length of a telescope is 36 cm. The focal lengths of its lenses can be 30 cm. 6 cm B -30 cm, -6 m C 30 cm, 6 m D 30 cm, 6 m

The length of an astronomical telescope is 40 cm. The focal lengths of its lenses will be

For a telescope, the focal lengths of two lenses are 30 cm and 10 cm. One acts as objective and the other as eye-piece. The length of the telescope is

In a terrestrial telescope, the focal length of objective is 90cm and of eye lens is 6 cm . If the final image is at 30cm , then the magnification will be

The radius of curvature of a concave mirror is 30 cm. What is its focal length ?

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.

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

An object is placed at the following distances from a concave mirror of focal length 15 cm, turn by turn : (a) 35 cm (b) 30 cm ( c) 20 cm (d) 10 cm Which position of the object will produce :

In a terrestrial telescope, the focal length of objective is 90cm , of inverting lens is 5 cm and of eye lens is 6 cm . If the final image is at 30cm , then the magnification will be the final image is at 30cm, then the magnification will be

Choose the correct alternative and write it along with its allotted alphabet: The focal length of a spherical mirror with radius of curvature 30 cm is ........ A. 30 cm B. 60 cm C. 15cm D. 45 cm

An object is placed 12 cm to the left of a converging lens of focal length 8 cm . another converging lens of 6cm focal length is placed at a distance of 30 cm to the right of the first lens. The second lens will produce