Page No 186:
Question 15:
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.
Object distance, u = −27 cm
Object height, h = 7 cm
Focal length, f = −18 cm
According to the mirror formula,
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The screen should be placed at a distance of 54 cm in front of the given mirror.
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The negative value of magnification indicates that the image formed is real.

The negative value of image height indicates that the image formed is inverted.