Question

? 15. The eyepiece of a microscope has a focal length of 1.25 cm and the objective lens focal length is 1.44 cm. (a) If the tube length is 18.0 cm, what is the angular magnification of the microscope? (b) What objective focal length would be required to double this magnification?

Answer 1

Answer:

[a] M = -250

[b] f = 0.720 cm

GIVEN,

fe = 1.25 cm

fo = 1.44 cm

L = 18.0 cm

[a] since, N = 25 cm, the angular magnification of the microscope is

                            M =L$M = L/ fo * N/fe = LN/ fo fe = 18.0 cm * 25 cm / 1.44 cm * 1.25 cm = -250$

[b] since the angular magnification is inversely proportional to the objective focal length when the other parameters are kept the same. To double the magnification the focal length should be halved. So, now objective focal length is :

                    f = 1.44cm / 2 = 0.720 cm