The direction of a ray of light incident on a concave mirror is shown by PQ, while direction in which the ray would travel after reflection is shown by four rays marked as A, B, C and D as shown in the figure. Which of the four rays correctly shows the direction of the reflected ray?
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Always remember the "parallel $\leftrightarrow$ focus" rule for concave mirrors:
- Incident parallel $\rightarrow$ Reflected through $F$.
- Incident through $F$ $\rightarrow$ Reflected parallel.
- Incident through $C$ $\rightarrow$ Reflected back through $C$ along the same path.
Step 1: Understanding the Question:
The question asks to identify the correct reflected path for a specific incident ray on a concave mirror based on standard rules of ray diagrams. \
Step 2: Detailed Explanation:
According to the properties of spherical mirrors:
1. A ray of light incident parallel to the principal axis of a concave mirror will, after reflection, pass through its principal focus ($F$).
2. In the provided diagram, the ray PQ is incident parallel to the principal axis (noted as a paraxial ray).
3. Analyzing the four proposed reflected paths:
- Ray A: Reflects upwards away from the axis (incorrect for concave reflection).
- Ray B: Passes through the center of curvature $O$ (incorrect for a parallel incident ray).
- Ray C: Passes through the principal focus $F$. This follows the fundamental rule.
- Ray D: Reflects straight down (incorrect).
Therefore, ray C correctly represents the reflected ray. Step 4: Final Answer:
The reflected ray is shown by ray C, which corresponds to option (2). \
