Physics Help Forum another plane mirror problem

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 Oct 29th 2009, 10:43 AM #1 Junior Member   Join Date: Sep 2009 Posts: 22 another plane mirror problem there is two plane mirror which is placed perpendicular to each other, as shown in the figure below. An object (indicated by the red dot) is placed in front of the mirrors and then there are 5 image formed (indicated by the blue dot 1,2,3,4,5, as illustrated in the figure) which image that the observer CANNOT see? I know the answer is image 4 and 3, but why??? I want to know why the observer cannot see image 3,4 and why he can see image 1,2,5... Thanks all
 Oct 29th 2009, 07:02 PM #2 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 Just draw the incident rays and the reflected rays according to the law of reflection,i.e. angle of incidence = angle of reflection. You will find that some images are impossible. __________________ Good results were achieved and the new task is to become a good doctor.
Oct 30th 2009, 09:07 AM   #3
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Join Date: Sep 2009
Posts: 22
 Originally Posted by werehk Just draw the incident rays and the reflected rays according to the law of reflection,i.e. angle of incidence = angle of reflection. You will find that some images are impossible.
but why those "impossible images "can be formed??

remember, the question is "when the object placed in front of the mirror, multiples images are formed, which one cannot be observed?" So the idea
of the question is that the "impossible "images are formed

 Oct 30th 2009, 08:31 PM #4 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 i don't mean impossible to form but impossible to reach the eyes of observers. Join a line between observer and the images 1-5, then propose the incident rays.For example, for image 5, Attached Thumbnails   __________________ Good results were achieved and the new task is to become a good doctor.

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