Unit: Optics
Year: 1993 Question#: 88
Question: The tip of a person's nose is 12 cm from a concave (converging) spherical mirror that has a radius of curvature of 16 cm. What is the distance from the mirror to the image of the tip of the person's nose?
(1 ) 8 cm
(2 ) 12 cm
(3 ) 16 cm
(4 ) 24 cm
What is this question really asking? includes image!!!!
Explanation by: LJP
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Answer 1
8 cm
INCORRECT
You probably subtracted the distance from the focal length to the object (16-12=8). return to top
Answer 2
12 cm
INCORRECT
You probably just assumed that since the object was 12 cm away, the image would be 12cm away. return to top
Answer 3
16cm
INCORRECT
You probably just assumed incorrectly that since the focal length was 16 cm, the image distance was 16 cm. return to top
Answer 4
24cm
CORRECT
since the center of the curvature is 16 cm from the mirror, the focal distance must be half of that, and therefore, 8 cm.
di = 24 cm return to top
What's this question really asking?
When an image is reflected in a concave mirror, what is the relationship between the distance of the focal length, the distance of the object and the distance of the image.
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