Question

A. How far from the objective lens is the first image formed?

A compound microscope has an objective lens of focal length 9.70 mm with an eyepiece of focal length 15.5 mm, and it produces its final image at infinity. The object to be viewed is placed 2.0 mm beyond the focal point of the objective lens

B. What is the overall magnification of this microscope?

Answer 1

given

fo = 9.70 mm
fe = 15.5 mm

A) object distance for objective lens, u = 9.7 + 2

= 11.7 mm

let v is the image distance

use, 1/u + 1/v = 1/fo

1/v = 1/fo - 1/u

1/v = 1/9.7 - 1/11.7

v = 56.7 mm (or) 5.67 cm <<<<<<-----------Answer

B) linear magnification of object lens, mo = -v/u

= -56.7/11.7

= -4.846

angular magnification of eye piece, Me = D/fe

= 250/15.5

= 16.1

so, the overll magnification, M = |mo|*Me

= 4.846*16.1

= 78.0 <<<<<<<---------------------Answer