# A compound microscope consists of an objective lens of focal length 2 cm and an eyepiece of focal

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A compound microscope consists of an objective lens of focal length 2 cm and an eyepiece of focal length 6.25 cm separated by a distance of 15 cm. How far from the objective should an object be placed in order to obtain the final image at

1. Least distance of distinct vision.

2. infinity

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1. ve = -25 cm

$\frac{1}{u_e}=\frac{1}{v_e}-\frac{1}{f_e}$ = $\frac{1}{-25}-\frac{1}{6.25}$

∴ u0 = 5 cm

Length of the tube, L= |v0| + |ue|

∴ v0 = 15 – 5 = 10

$\frac{1}{u_0}=\frac{1}{v_0}-\frac{1}{f_0}$ = $\frac{1}{10}-\frac{1}{2}$

ue = -2.5 cm.

2.  ∴ v0 = 15 – f= 15 – 6.25 = 8.75

$\frac{1}{u_0}=\frac{1}{v_0}-\frac{1}{f_0}$$\frac{1}{8.75}$ - $\frac{1}{2}$

u0 = -2.59 cm