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Two plane mirrors M1 and M2 have a length of 2 meters each and are 10 cm apart. A ray of light is incident on one end of mirror M2 at an angle of 30 degrees. What is the number of reflections light undergoes before reaching the other end?

I solved it in the following way:

In each reflection the distance moved = 10 x tan(30)

= 5.77 cm

Therefore the number of reflections before it reaches

the other end = 200/5.77

= 34

But the answer given in my book is 170. Please help.

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# Homework Help: Number of reflections undergone by light ray between 2 plane mirrors

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