Question

There are two plane mirrors with reflecting surface facing each other. Both the mirrors are moving with speed $v$ away from each other. A point object is placed between the mirrors. The velocity of the image formed due to $n-th$ reflection will be :

• A. $nv$
• B. $2nv$
• C. $3nv$
• D. $4nv$

Answer 1

Answer: (B)

$2nv$

As you can see the first image formed is at a distance equal to $2$ times of the distance between the mirrors. Similarly the distance between nth order image will be $2n$ times that distance.

Hence we can conclude from this that the speed of nth order image will be equal to $2n$ times the speed of mirror.

The velocity of the image formed due to $n^{th}$ reflection will be equal to $2nv$.