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Question
Describe the nature of image formed when the object is placed at a distance of 20 cm from a concave mirror of focal length 10 cm
Solution
Object distance (u) = - 20 m ( negative, due to sign convention)
Focal length (f) = -10 m ( negative, due to sign convention)
Image distance = ?
From the mirror formula, we know that:
`1/v+1/u=1/f`
or `1/v+1/-20=(-1)/10`
or `1/v-_20^1=_10^-1`
or `1/v=(-1)/10+1/20`
or `1/v=-1/20orv=-20m`
Here, the negative sign means that the image is formed on the left side of the mirror. Thus, it is a real and inverted image, formed at a distance of 20 m from the mirror.
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