Question

In an compound microscope, the focal lengths of two lenses are 1.5 cm and 6.25. an object is placed at 2 cm from objective and the final image is formed at 25 cm from the eyepiece. The distance between the two lenses is (in cm)

• A. 6
• B. 7.75
• C. 9.25
• D. 11

Answer 1

The correct option is D 11

$\frac{1}{f_0}=\frac{1}{v_0}+\frac{1}{4_0};\frac{1}{1.5}=\frac{1}{v_0}+\frac{1}{2}\frac{1}{v_0}=\frac{1}{1.5}-\frac{1}{2}=\frac{0.5}{3}=\frac{5}{30}{v}_0=6cm\frac{1}{f_e}=-\frac{1}{D}-\frac{1}{v_e}{v}_e=5cm\frac{1}{6.25}=-\frac{1}{25}L=v_0+v_e\frac{1}{6.25}+\frac{1}{25}=-\frac{1}{v_e}=6+5\frac{4+1}{25}=-\frac{1}{v_e}L=11cm$