A source of light is located at double focal lengths from convergent lens. The focal length of lens is f =30 cm. At what distance from lens should a plane mirror be placed so that the ray reflected from mirror are parallel after passing through lens for second time ?

Question

A source of light is located at double focal lengths from convergent lens. The focal length of lens is f =30 cm. At what distance from lens should a plane mirror be placed so that the ray reflected from mirror are parallel after passing through lens for second time ? (A) 60 cm (B) 30 cm (C) 15 cm (D) 45 cm

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<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/663449f710c240294caa73fa7b8fea61-.png" /> 2 x=30 cm x=15 cm Distance of mirror from lens =30+ x =45 cm

Q. A source of light is located at double focal lengths from convergent lens. The focal length of lens is $f = 30 c m$ . At what distance from lens should a plane mirror be placed so that the ray reflected from mirror are parallel after passing through lens for second time ?

60 cm

30 cm

15 cm

45 cm

$2 x = 30 c m$
$x = 15 c m$
Distance of mirror from lens
$= 30 + x = 45 c m$

Q. A source of light is located at double focal lengths from convergent lens. The focal length of lens is f=30cm. At what distance from lens should a plane mirror be placed so that the ray reflected from mirror are parallel after passing through lens for second time ?