Question

Q. (a) Why magnification is taken negative for real images and positive for virtual images?
(b) Why convex mirror is used in rear view mirrors and not concave mirror?
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Answer 1

(a) If image is real, it will be inverted which means height of image will be taken as negative.

Also, the height of object is always positive.

Now as magnification = Height of image / Height of object.

Therefore, in case of real image,Magnification = Height of image (-) / height of object (+)=Negative.

So, Magnification will be negative.

Similarly, if image is virtual, it will be erect.Therefore, in case of virtual image,Magnification = Height of image (+) / height of object (+)= PositiveSo, Magnification will be positive.

(b) Convex mirror is commonly used in rear view mirrors in vehicles because it gives an erect, virtual, full size diminished image of distant objects with a wider field of view. Thus, convex mirrors enable the driver to view much larger area which is not possible with a concave mirror.

Answer 2

Answer:

real images are formed on the side where the values are taken to be negative and same for virtual images.this is according to the rules of sign convention

convex mirrors are also known as converging mirrors. hence to show a larger area in a small space coven mirrors are used vice a versa cocave mirrors would enlarge the image hence they are not used