I wonder, how does a car rear-view mirror work?
When there is a car behind me with high-beam, all I do is flip a tong at the bottom of the mirror to relax the lights!
Are there two mirrors in it, one darker than the other?
[Physics] How do car rear-view mirrors work?
everyday-lifeopticsreflectionvision
Related Solutions
The mirror is made convex in order to provide a wider field of view. Thus, the objects in it appear smaller than on a flat mirror, and your brain infers they should be further away.
The reason is simple geometry.
Consider the following image.
(source: tutorvista.com)
Then you can clearly see the image at $O_{3}$ is due to double reflection from mirrors $M'$ and $M$. In general all the images including the object will be on a circle centered around the intersection point between two mirrors. For two mirrors inclined at $n^{0}$ with respect to each other.The number of images are $\frac{360}{n}-1$. I do not know the proof of the last formula. As far as I know it is because reflection of one mirror to another forms a virtual mirror and the number of virtual mirrors are $\frac{360}{n}$ http://www.learnquebec.ca/export/sites/learn/en/content/curriculum/mst/images/CHAPITRE523.GIF Final image from both the mirror coincides hence we have to subtract $1$.
Best Answer
For manual anti-glare mirrors, the glass is actually a prism with the silvered rear surface not parallel to the front surface
In day-time position, drivers are seeing reflections from the rear surface with large amounts of reflected light reaching their eyes
In night-time anti-glare position, drivers are seeing reflections from the front surface of the glass, with much less light going into their eyes; the brighter rear reflection goes elsewhere. This is still enough to distinguish headlights behind, but not much else, and substantially less than if the day-time position was used at night, so reducing the contrast which could be blinding if the following vehicles were foolish enough to use full-beam headlights
See https://en.wikipedia.org/wiki/Rear-view_mirror#Anti-glare for more (and the automated alternative) which has these two diagrams