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2 plane mirrors each of length 10cm are placed at a separation of 1 cm (parallel to each other). a ray of light is incident at an angle of 45 on one of the mirrors as shown . how many times it will undergo reflection before going out from the other end ??

2 plane mirrors each of length 10cm are placed at a separation of 1 cm (parallel to each other). a ray of light is incident at an angle of 45 on one of the mirrors as shown . how many times it will undergo reflection before going out from the other end ??

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Grade:12th pass

2 Answers

Shivam Chopra
45 Points
7 years ago
It will undergo a total of 10 reflections.
8 inside the mirror, 1 during entering & 1 during exit.
Here, when the light enters, during 1st reflection, angle of reflection is 45 degree.
Now, for the triangle formed, one angle is 45 degree &, base is 1cm.
So, applying tan 45 = perpendicular / base, length of perpendicular comes to be 1 cm.
So, during one reflection, it covers a horizontal distance of 1 cm.
So, it will cover distance of 10 cm after 10 reflections
Please appreove it if you like.
maitreyee jagannath
36 Points
7 years ago
plx do answer the 2nd question ..

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