Linear Magnification – The ratio of the height of the image to that of the object is called as linear magnification or simply magnification and is denoted by the letter m. thus
Example 14.1:
An object is placed at a distance of 30 cm from a concave mirror. Find the nature and position of the image if focal length of the mirror is 5 cm.
Solution: we have
Position of image:The image is in front of the concave mirror at a distance of 6 cm from the mirror.
Nature of image: Since q is positive, therefore, image is real.
Example 14.2: how far from a concave mirror of focal length 20 cm would you place an abject to get an image three times enlarged?
Solution: there are two possible solutions of this question.
(i) When image is real
F = 20 cm p = ?
As magnification is three times thus
Thus object should be placed at a distance of 26.7 cm from concave mirror.
(ii) When the image is virtual
The image is erect and behind the mirror.
