- #1
Pete_L
- 27
- 1
Consider an upright cylindrical concave mirror with a point source located at the focal point of the mirror. By upright I mean that the mirror is plane in the vertical direction and a concavity in the horizontal plane.
Now it seems likely that you would see a virtual image of the point source looking at the mirror in the vertical plane coincident with the principle axis of the mirror. The point source radiating to the vertex of the mirror "sees" a plane reflective surface both vertically and horizontally.
So however what happens if the viewer looks to one side (laterally) of the principal axis? Off to one side, the point source as before is in the vertical plane reflected according to reflection from a plane mirror. But horizontally, the reflected light ray is parallel with the principal axis as the point source is located at the focal point of the mirror. Will the virtual image of the point source in this case disappear completely? Or, if a virtual image does occur, then where is it located?
This is an interesting problem I think that I haven't seen discussed in the standard treating of reflection by concave mirrors.
Let me have your thoughts, please-
Pete
Now it seems likely that you would see a virtual image of the point source looking at the mirror in the vertical plane coincident with the principle axis of the mirror. The point source radiating to the vertex of the mirror "sees" a plane reflective surface both vertically and horizontally.
So however what happens if the viewer looks to one side (laterally) of the principal axis? Off to one side, the point source as before is in the vertical plane reflected according to reflection from a plane mirror. But horizontally, the reflected light ray is parallel with the principal axis as the point source is located at the focal point of the mirror. Will the virtual image of the point source in this case disappear completely? Or, if a virtual image does occur, then where is it located?
This is an interesting problem I think that I haven't seen discussed in the standard treating of reflection by concave mirrors.
Let me have your thoughts, please-
Pete