
#1
Jun606, 01:59 PM

P: 424

Sir,
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. 



#2
Jun606, 02:10 PM

Mentor
P: 40,889

Your answer and method make sense to me; the book's answer does not.




#3
Jun606, 02:13 PM

Emeritus
Sci Advisor
PF Gold
P: 9,789





#4
Jun606, 04:46 PM

P: 424

Number of reflections undergone by light ray between 2 plane mirrors
Sir,
I kindly request you all to tolerate the erroneous questions of my book. There are about 150 questions in each unit out of which say about 7 to 8 questions have wrong answers. That is why I am still using it. I hope to get it corrected with your help.Thanks for your guidance. 


Register to reply 
Related Discussions  
Nearsightedness and Plane Mirrors  Introductory Physics Homework  2  
Mirrors and reflections  General Physics  7  
Number of images formed by 3 mutually perpendicular plane mirrors  Introductory Physics Homework  1  
Decrease in intensity of light on undergoing successive reflections  Introductory Physics Homework  1  
unusual light reflections  General Discussion  1 