Welcome to brain Stuff from how stuff Works dot com where smart Happens. Hi, I'm Marshall Brain. Have you ever used the glare resistance setting on your car's rear view mirror and wondered what's going on? How can the same piece of glass have two different amounts of reflection. If you stand in front of a normal window in your house at night, inside the house with the indoor lights on, you'll be able to see your reflection in the glass
quite clearly. A car's mirror takes advantage of that same effect. The mirror in your car isn't ground flat. The front glass surfaces at an angle to the back mirrored surface, so if you were to look at this mirror out of its casing, it would be wedge shaped, with the thicker edge up at the top. When you flip the mirror, the back mirrorred surface usually points towards the dark ceiling,
so you don't see that image. What you see instead is the image reflecting off the front of the glass, and this is much dimmer than the pure reflected image, so it doesn't hurt your eyes. Be sure to check out our new video podcast, Stuff from the Future. Join how Stuff Work staff as we explore the most promising and perplexing possibilities of tomorrow. The House Stuff Works iPhone app has arrived. Download it today on iTunes.