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प्रश्न
If an object is placed at a distance of 10 cm in front of a concave mirror of a focal length of 20 cm, the image formed will be ______.
विकल्प
Real and 20 cm in front of the mirror
Real and 6.67 cm in front of the mirror.
Virtual and 20 cm behind the mirror.
Virtual and 6.67 cm behind the mirror.
उत्तर
If an object is placed at a distance of 10 cm in front of a concave mirror of a focal length of 20 cm, the image formed will be virtual and 20 cm behind the mirror.
Explanation:
Given, f = - 20 cm; u = - 10 cm
Using the formula
`1/"f" = 1/"v" + 1/"u"`
`=> 1/(- 20) = 1/v - 1/10`
`=> 1/10 - 1/20 = 1/v`
`=> 1/v = 1/20`
⇒ v = 20 cm
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