2006-09-08 02:47:22 · 6 answers · asked by sim 2 in Science & Mathematics ➔ Physics
Interesting question. The answer you get seems to depend on how you "make" your plane mirror as the limit of a convex or concave mirror. A concave mirror has a +ive focal length, and as you make it more and more flat, the focal point moves away from the surface. The limit is a flat mirror with a focal point at +infty. On the other hand, for a convex mirror, the opposite obtains: you get a flat mirror with a focal point at -infty.
In fact both happen at once: the other side of a convex mirror is concave, and vice-versa. So one way of thinking about it is that there are two focal points for any mirror, moving in opposite directions, which both end up infinitely far away from theire respective sides of the mirror. In this case, "+" and "-" are just labels for the words "left" and "right".
2006-09-08 03:21:22 · answer #1 · answered by Benjamin N 4 · 0⤊ 0⤋
The focal lenght is infinity since the rays technically converge at infinity.
2006-09-08 10:02:04 · answer #2 · answered by louzadodude 2 · 0⤊ 0⤋
Infinity. Light does not converge. Asymptodical travel of light beams seem to meet at infinity. The lines are parallel, you see?
Really, they do not meet because they do not coverge. So no focal point.
Infinity is a concept and it does not really exist. Get it?
2006-09-08 10:15:01 · answer #3 · answered by Nightrider 7 · 0⤊ 0⤋
focal length of plane mirror is infinity.......
2006-09-08 13:17:51 · answer #4 · answered by manish s 1 · 0⤊ 0⤋
no focal length or may be infinity.
2006-09-08 10:00:34 · answer #5 · answered by dwarf 3 · 0⤊ 0⤋
no focal length.
2006-09-08 09:50:25 · answer #6 · answered by maczh2002 2 · 0⤊ 0⤋