Question
Two convex lens of same focal length but their aperture and focal lengths 5 cm and 10 cm are used as object lens in two astronomical telescope.
(a) What will be the ratio of their
(i) resolving power
(ii) magnifying power
(b) Compare the intensity of images formed in these cases.
Solution
Given, two convex lens of same focal length.
Aperture of the first lens, D1 = 5 cm
Aperture of second lens, D2 = 10 cm
(i) Ratio of resolving power is,
(ii) Ratio of magnifying power is given by,
(b) Intensity of image is directly proportional to the size of aperture hence, it will also have a ratio of
Aperture of the first lens, D1 = 5 cm
Aperture of second lens, D2 = 10 cm
(i) Ratio of resolving power is,
(ii) Ratio of magnifying power is given by,
(b) Intensity of image is directly proportional to the size of aperture hence, it will also have a ratio of
