Concave and Convex Mirrors
The purpose of this lab is to observe the images produced by convex and concave mirrors; to analyze the geometry behind reflected rays on the two mirrors, how each mirror magnifies in a certain way (and sometimes flips upside down); to understand the relationship between the two mirror's different curvatures, focus points, and how they would affect the object's image to appear having different height and at different distance.
Questions / guidelines
I. Convex Mirror
1. Place an object in front of the convex mirror.
A. The image appears smaller than the actual size of object.
B. The image is upright.
C. The image is located farther relative to the position of the mirror and object.
2. Move the object closer.
The object grows in size / appears bigger as it gets closer. It also appears to more bent/ curved.
3. Move object further.
The object grows smaller and less bent.
Diagram of Convex Mirror
II. Concave Mirror
1. Place an object in front of mirror
A. The image appears larger than the object.
B. The image appears inverted when it's located behind (away) from the curvature point. When the object is close, the image would appear upright.
C. The image appears to be located relatively closer than actual distance of the object and mirror.
Object appears inverted
2. Move the object close.
The image grows larger in height (size), inverted. When it's close enough, the image would blur and when it's even closer, it would appear upright and magnified.
3. Move the object further.
If the object started off very close, it would appear upright and magnified; as the object is brought away, it would become smaller, then it would blur, then it would appear inverted and smaller. If the object started off not too close, it would start off appearing inverted. As it is brought away, it would grow less in size.
Concave mirror diagram
The graph at the end of Lab 9. d_0 = 10.5 +/- 0.1 cm, d_i = 3.2 +/- 0.1 cm, h_0 = 2.2 +/- 0.1 cm, h_i = 0.7 cm.
M = 0.3 +/- 0.2
Error Analysis
The magnification can be represented as
m = y' / y = - (s' / s)
whereas y' is the height of the image, and y is the height of object (actual). The s' are distances, just like height. m simply gives the ratio of y' and y and actual vs appearance distance.
The main source of error is due to the magnification of the ruler used when measuring the distance; while measuring the distance of object can be done easily by simply using a ruler, measuring the distance of image cannot be done by simply using a ruler; the ruler in the mirror is an image, a distorted image. An image of 1 cm is not 1 cm in real world.
To fix it, a detailed photograph/ still image should have been taken, and a comparison between the actual vs appearance distance can be made then by measuring the difference of distances (actual and image) from the photograph.
END.
Um, smile...? ;)
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