The magnifying power of a microscope with an objective of `5 mm` focal length is 400. The length of its tube is `20cm.` Then the focal length of the eye`-` piece is

A telescope has magnification 5 and length of tube 60cm then the focal length of eye piece is–

A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has focal length 0.5cm and the tube length is 6.5cm . Find the focal length of the eye-piece.

The magnifying power of terrestrial telescope is 25 when it is in normal adjustment and the length of the telescope is 124 cm. If the focal length of the erecting lens is 5 cm, the focal lengths of the objective and the eye-piece are respectively.

The magnifying power of a telescope is 10. What would be its new magnifying power if the focal length of the objective is doubled and the focal length of the eyepiece is halved ?

The focal length of the eye-piece of compound microscope is

A compound microscope has a magnifying power of 100 when the image is formed at infinity. The objective has a focal length of 0.5 cm and the tube length is 6.5 cm. Find the fbcal length of the eyepiece.

The focal length of the objective lens of a telescope is 50 cm If the magnification of the telescope is 25, then the focal length of the eye-piece is

In a compound microscope , the magnificent virtual image is found at a distance of 25 cm from the eye-piece . The focal length of its objective lens is 1 cm. If the microspore is 20 cm , then the focal length of the eye-piece lens ( in cm) is .................

An astronomical telescope has a magnifying power 10. The focal length of the eye piece is 20 cm. the focal length of the objective is -