Question

4. 4) In order to get as large of a magnification as possible for a microscope, you would need

   1. A large focal length objective, and a large focal length eyepiece

   2. A large focal length objective, and a small focal length eyepiece

   3. A small focal length objective, and a small focal length eyepiece

   4. A small focal length objective, and a large focal length eyepiece.

5. 5) If we have a Galilean telescope with an objective lens of fo = 125 cm and an eyepiece lens of fe = -25 cm, then our telescope would have a magnification and a length of:

   a. m=5,L=150cm
   b. m=-0.2,L=100cm
   c. m=-5,L=100cm
   d. m = -5, L = 150 cm

Answer 1

4)In order to get large magnification as possible for a microscope, we need small focal length objective, and a small focal length eyepiece.The reason is as follows.

Magnifying power of a microscope(M) is given by

M=L/fo(1+D/fe) where L=length of microscope, fo= focal length of objective lens, fe=focal length of eyepiece.

D=least distance of distinct vision . Hence for large magnification fo and fe should be small

5)Galilean telescope consist of objective lens of convex lens and eye piece of concave lens. Hence final image is erect

Magnification of Galilean telescope =fo/fe=(125/-25)=-5

Length of telescope=-=125-25=100cm