Question

There are two plane mirror with reflecting surfaces facing each other. Both the mirrors are moving with the speed of ν away from each other. A point object is placed between the mirrors. The velocity of the image formed due to the nth reflection will be

(A) nv

(B) 2nv

(C) 3nv

(D) 4nv

Answer 1

The correct option is (B) 2nv.

Explanation:

With respect to mirror1 the object is going array from mirror. So first image will also more away w.r.t mirror 1 with same speed v. So with respect to object O the image speed is

Now this image becomes object for mirror 2. With respect to mirror 2 the image is going away towards left with speed 3v. So its second image will more away towards right with speed 3v w.r.t mirror 2. Hence speed w.r.t O will be 3v + v = 4v.

Hence for nth image vimage = 2nv