The magnifying power of a telescope is `9.` When it is adjusted for parallel rays the distance between the objective and eyepiece is `20cm`. The focal lengths of lenses areA. 10 cm, 10 cmB. 15 cm, 5 cmC. 18 cm, 2 cmD. 11 cm, 9 cm

The magnifying power of a telescope is `9.` When it is adjusted for pa

1.	The magnifying power of a telescope is `9.` When it is adjusted for parallel rays the distance between the objective and eyepiece is `20cm`. The focal lengths of lenses areA. 10 cm, 10 cmB. 15 cm, 5 cmC. 18 cm, 2 cmD. 11 cm, 9 cm
Answer» Correct Answer - C Here, `M = (f_0)/(f_e) = 9 :. f_0 = 9 f_e` …..(i) When adjusted for parallel rays, the distance between the objective anf eye piece is `f_0 + f_e = 20 cm` Using (i), `9 f_e + f_e = 20` or `f_e = 2 cm` From (i), `f_0 = 9 xx 2 cm = 18 cm`.

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The magnifying power of a telescope is `9.` When it is adjusted for parallel rays the distance between the objective and eyepiece is `20cm`. The focal lengths of lenses areA. 10 cm, 10 cmB. 15 cm, 5 cmC. 18 cm, 2 cmD. 11 cm, 9 cm

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