Unit: optics
Year: 1990 Question#: 91
Question: On the diagram which shows four rays of light from the object ab incident upon a spherical mirror whose focal length is 0.04 meter. Point f is the principal focus of the mirror, point c is the center of curvature, and point o is located on the principal axis. Which ray of light will pass through f after it is reflected from the mirror?
(1 ) 1
(2 ) 2
(3 ) 3
(4 ) 4
What is this question really asking?
Explanation by: IrinaK
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Answer 1
1
INCORRECT
This ray of light will reflect back toward the center at point c not at point f . return to top
Answer 2
2
CORRECT
Any ray coming parallel to the principal axis will reflect and pass through the focus f. return to top
Answer 3
3
INCORRECT
This ray will reflect at the same angle it came at point o . return to top
Answer 4
4
INCORRECT
This ray will do the opposite of the ray 2 because it will pass through f first and then it will reflect parallel to the principal axis. return to top
What's this question really asking?
It is asking about the way rays principle reflect off the concave mirror. return to top
