The magnifying power of a telescope is 9. When it is adjusted for parallel rays. The distance between the objective and eyepiece is 20 cm. The focal length of its lenses are.

Q. An astronomical telescope and a Galilean telescope use identical objective lenses. They have the same magnification, when both are in normal adjustment. The eyepiece of the astronomical telescope has a focal length

f .

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The distance between the objective lens and the eye lens of an astronomical telescope when adjusted for parallel light is 100cm. The measured value of the magnification is 19. The focal length of objective and eyepiece are

The correct option is C 95cm and 5cmL=100cmf0+fe=100 .....(1)m=f0fe19=f0fe ⇒ f0=19fe Substituting in Equation (1)19fe+fe=100 fe=5cm∴f0=19×5So, fo=95cm

The distance between the objective lens and the eye lens of an astronomical telescope when adjusted for parallel light is $100 c m$ . The measured value of the magnification is $19$ . The focal length of objective and eyepiece are

The correct option is C $95 c m$ and $5 c m$
$L = 100 c m$
$f_{0} + f_{e} = 100$ .....(1)
$m = \frac{f_{0}}{f_{e}}$
$19 = \frac{f_{0}}{f_{e}}$ $\Rightarrow$ $f_{0} = 19 f_{e}$
Substituting in Equation (1)
$19 f_{e} + f_{e} = 100$
$f_{e} = 5 c m$
$∴ f_{0} = 19 \times 5$
So, $f_{o} = 95 c m$