An object viewed from a near point distance of 25 cm, using a microscopic lens with magnification ' 6 ', gives an unresolved image. A resolved image is observed at infinite distance with a total magnification double the earlier using an eyepiece along with the given lens and a tube of length 0.6 m, if the focal length of the eyepiece is equal to cm.

Question

An object viewed from a near point distance of 25 cm, using a microscopic lens with magnification ' 6 ', gives an unresolved image. A resolved image is observed at infinite distance with a total magnification double the earlier using an eyepiece along with the given lens and a tube of length 0.6 m, if the focal length of the eyepiece is equal to cm. (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

For simple microscope, m=1+(D/f0) 6=1+(D/f0) 5=(25/f0) f0=5 cm For compound microscope, m=(l ⋅ D/f0 ⋅ fe) 12=(60 × 25/5 ⋅ fe) fe=25 cm

For simple microscope, m=1+f0​D​ 6=1+f0​D​ 5=f0​25​ f0​=5cm For compound microscope, m=f0​⋅fe​l⋅D​ 12=5⋅fe​60×25​ fe​=25cm

For simple microscope,
$m = 1 + \frac{D}{f _{0}}$
$6 = 1 + \frac{D}{f _{0}}$
$5 = \frac{25}{f _{0}}$
$f_{0} = 5 c m$
For compound microscope,
$m = \frac{l \cdot D}{f _{0} \cdot f _{e}}$
$12 = \frac{60 \times 25}{5 \cdot f _{e}}$
$f_{e} = 25 c m$