How can a plane mirror be thought of as a special case of a spherical mirror? What is the focal length of a plane mirror? Does the spherical mirror equation work for plane mirrors with this choice of focal length? What is the transverse magnification for any image produced by a plane mirror?
2007-04-01 12:53:00 · 2 answers · asked by Sir Guitarist 2 in Science & Mathematics ➔ Physics
A plane mirror is a special case of a spherical mirror because it has no focus. Its focal lenght is thus infinity. The equation 1/f = 1/o + 1/i (f is focal lenght, o is object distance, i is image distance) holds true for plane mirrors:
f is infinity. 1 / infinity can be thought of as 1 divided by an immensely huge number, which makes the value very close to 0.
The distance from the mirror to the object is equal to the distance from the mirror to the image in a plane mirro, but the image distance is negative. Therefore, if o=i, 1/o + -1/o is equal to 0, and the equation holds true (it's just not useful).
The magnification m=Hi/Ho (height image / height object) is always "1" in a plane mirror.
The equation m= -i/o also holds true (o = -i)
m = -(-o) / o = o/o = 1.
2007-04-01 13:06:29 · answer #1 · answered by pedros2008 3 · 0⤊ 0⤋
As the radius of curvature of a spherical mirror goes to â, that results in a plane mirror. Since the focal length of a spherical mirror is r/2, the focal length of a plane mirror is â. The equations break down at this focal length, and the magnification is unity.
2007-04-01 12:58:53 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋