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Question
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 ______.
Options
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.
Solution
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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