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Question
A concave mirror produces three times magnified image on a screen. If the object is placed 20 cm in front of the mirror, how far is the screen from the object.
Solution
Here,
Magnification, m = - 3 (As the image is real)
Object distance, u = - 20 cm
Image distance, v = ?
We know, `m=−v/u`
`−3=−(v/(−20))`
`⇒v=−60 cm`
The screen is placed in front of the mirrors at a distance of 60 cm from the pole of the mirror.
Thus, the screen is placed 40 cm (= 60 cm - 20 cm) away from the object.
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