Single Choice

In a compound microscope, the focal lengths of two lenses are 1.5 cm and 6.25 cm. If an object placed at 2 cm from objective and the final image is formed at 25 from eye lens, the distance between the two lenses is

A$$6.00 cm$$
B$$7.75 cm$$
C$$9.25 cm$$
D$$11.0 cm$$
Correct Answer

Solution

Answer : D Solution : $$L=u_0+u_e=\dfrac{u_0f_0}{(u_0-f_0)}+\dfrac{f_eD}{f_e+D}$$ $$\Rightarrow L=\dfrac{2\times 1.5}{(2-1.5)}+\dfrac{6.25\times 25}{(6.25+25)}=11cm$$

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