Question

The ratio of the distance of the cross wires from field lens and distance between lenses in Ramsden's eyepiece is

• A. $2:3$
• B. $3:4$
• C. $3:8$
• D. $3:2$

Answer 1

The correct option is C $3:8$

Distance the crosswires from field lens is $\frac{\delta }{4}$.
Distance between lenses in ramsden's eye piece is $\frac{2}{4}\delta$.
So, ratio $=\frac{\frac{\delta }{4}}{\frac{2\delta }{3}}$ $=\frac{3}{2\times 4}$ $=\frac{3}{8}$

Hence correct option is C.