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Question
The direction of ray of light incident on a concave mirror is shown by PQ while directions in which the ray would travel after reflection is shown by four rays marked 1, 2, 3 and 4 (figure). Which of the four rays correctly shows the direction of reflected ray?
Options
1
2
3
4
Solution
2
Explanation:
The ray PQ of light passes through focus F and incident on the concave mirror, after reflection, should become parallel to the principal axis as shown by ray 2 in the figure.
Important points: We can locate the image of any extended object graphically by drawing any two of the following four special rays:
- A ray initially parallel to the principal axis is reflected through the focus of the mirror (1).
- A ray passing through the center of curvature is reflected back along itself (3).
- A ray initially passing through the focus is reflected parallel to the principal axis (2).
- A ray incident at the pole is reflected symmetrically.
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