Question 371: Ray Optics

Question

In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is $$I$$. The magnification of the telescope is

Accepted Answer

Magnification by eye piece
m = $${f \over {f + u}}$$
$$ \Rightarrow $$ $$ - {I \over L} = {{{f_e}} \over {{f_e} + \left[ { - \left( {{f_0} + {f_e}} ight)} ight]}}$$ = - $${{{f_e}} \over {{f_0}}}$$
$$ \Rightarrow $$ $${I \over L} = {{{f_e}} \over {{f_0}}}$$
$$ 	herefore $$ Magnification, M = $${{{f_0}} \over {{f_e}}}$$ = $${L \over I}$$

Answer

$${{L + I} \over {L - I}}$$

Answer

$${L \over I}$$

Answer

$${L \over I} + 1$$

Answer

$${L \over I} - 1$$

Ray Optics

In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is $I$. The magnification of the telescope is

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