Question

2.5 Bouncing Laser Four mirrors are arranged in a square, with their reflective sides pointing inwards. There is an infinitely small gap at each corner, through which a laser beam may pass. How many distinct ways can a laser beam be fired through one corner, bounce off exactly 68 walls, and then exit through another corner?

          2.5 Bouncing Laser
Four mirrors are arranged in a square, with their reflective sides pointing
inwards. There is an infinitely small gap at each corner, through which a
laser beam may pass. How many distinct ways can a laser beam be fired
through one corner, bounce off exactly 68 walls, and then exit through
another corner?

2.5 Bouncing Laser
Four mirrors are arranged in a square, with their reflective sides pointing
inwards. There is an infinitely small gap at each corner, through which a
laser beam may pass. How many distinct ways can a laser beam be fired
through one corner, bounce off exactly 68 walls, and then exit through
another corner?

Added by Stacy H.

Physics

John D. Cutnell, Kenneth W. Johnson 7th Edition

Chapter 25

Instant Answer

Solved by Expert Moni Gupta

Step 1

Since the laser beam must bounce off exactly 68 walls, it means that it must make 34 reflections. Now, let's consider the first reflection. The laser beam can bounce off any of the 4 mirrors, so there are 4 possible choices for the first reflection. After the Show more…

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2.5 Bouncing Laser Four mirrors are arranged in a square, with their reflective sides pointing inwards. There is an infinitely small gap at each corner, through which a laser beam may pass. How many distinct ways can a laser beam be fired through one corner, bounce off exactly 68 walls, and then exit through another corner?