Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# If an Object Far Away from a Convex Mirror Moves Towards the Mirror, the Image Also Moves. Does It Move Faster, Slower Or at the Same Speed as - Physics

Short Note

If an object far away from a convex mirror moves towards the mirror, the image also moves. Does it move faster, slower or at the same speed as compared to the object?

#### Solution

The image of the object moves slower compared to the object. It can be explained using the mirror formula :
$\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$
We know that for a convex mirror, the object distance (u) is positive, image distance (v) is negative and the focal length (f) is also negative. Thus mirror formula of a convex mirror is:
$\frac{1}{u} - \frac{1}{v} = - \frac{1}{f}$
As u = +ve
$\frac{1}{v} - \frac{1}{f} > 0$
$\frac{1}{v} > \frac{1}{f}$
$v < f$
Therefore, the image is always formed within the focal length of the mirror. Thus, the distance moved by the image is much slower than the distance moved by the object.

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#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 18 Geometrical Optics
Short Answers | Q 9 | Page 410