Elitmus
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Four mirrors are erected perpendicular to the ground to form a rectangle ABCD.The longer mirror are facing inwards & negligible gap between the corners.A laser beam is shot at mirror BC through the gap of point A,in a plane parallel to the ground.
i)How many lines will the laser beam bounce of a mirror surface before exiting the rectangle from point C.If the beam travels a total distance of 25cm inside the rectangle?
options:5,4,3,none
ii)How many times will the laser beam bounce mirror surface before exiting the rectangle from point A.if the beam travels shortest possible distance inside the rectangle?
options:22,15,4,none.
Read Solution (Total 4)
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- rectangle will be A________D
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B_/______C i have taken the simplest case when the ray is striking 2 times and exiting making three lines..
for the first question .. the trick is,the lines inside the rectangle are if equal length and to exit from C the number of total lines will always be odd.. hence option 4 ruled out.. so its 3 or 5 .. 3 cant be the answer as 25 cant be divided equally in 3 parts so its 5..
ii) shortest possible distance
A___________D
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i cant make you visualize bettr than this dotted ray is the ray coming inside getting reflected 4 times and returning back from A
- 10 years agoHelpfull: Yes(2) No(1)
- A____B
| | I) 4 ( first strike in BD then CD then AB then BD then it wll be
| | out)
|____|
C D - 10 years agoHelpfull: Yes(1) No(4)
- hey guys i can't understand this ques...please explain with the correct answer
- 10 years agoHelpfull: Yes(0) No(0)
- the question is how many times not no of lines, so for entering from And exiting from C , its will always be even no of times
- 5 years agoHelpfull: Yes(0) No(0)
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