(a) Draw a ray diagram of compound microscope for the final image formed at least distance of distinct vision? (b) An angular magnification of 30X is desired using an objective of focal length 1.25 cm and an eye piece of focal length 5 cm. How will you set up the compound microscope for the final image formed at least distance of distinct vision?

(a) Draw a ray diagram of compound microscope for the final image formed at least distance of distinct vision?
(b) An angular magnification of 30X is desired using an objective of focal length 1.25 cm and an eye piece of focal length 5 cm. How will you set up the compound microscope for the final image formed at least distance of distinct vision?

ANS 8
(a)

Diagram of Compound Microscope for the final image formed at D:

(b) m୭ = 30, f୭ = 1.25 cm, fୣ = 5 cm
when image is formed at least distance of distinct vision, D = 25cm
Angular magnification of eyepiece

As the objective lens forms the real image,

using lens equation, u୭ = −1.5 cm, v୭ = −5 × (−1.5)cm = +7.5 cm
Given vୣ = −D = −25 cm, fୣ = +5 cm, uୣ = ? using again lens equation uୣ =
ଶହ
଺
Thus, object is to be placed at 1.5 cm from the objective and separation between the two lenses should be
L = v୭ + Iuୣ
l = 11.67 cm