Physics
Assertion (A): When light passes through a triangular prism, it is observed that for two angles of incidence, the angle of deviation is the same.
Reason (R): According to the principle of reversibility, the light retraces the path in reversing the direction.
- A and R are true, and R is the reason for A.
- A and R are true, and R is not the reason for A.
- A is true, but R is false.
- A is false, but R is true.
Refraction Plane Surfaces
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Answer
A and R are true and R is the reason of A.
Explanation:
Assertion (A) is true: When light passes through a triangular prism, the angle of deviation first decreases with increasing angle of incidence, reaches a minimum, and then increases again. This means there are two angles of incidence that result in the same angle of deviation—one on either side of the minimum deviation point.
Reason (R) is also true: The principle of reversibility of light states that if the direction of a light ray is reversed, it retraces its original path. This principle explains why the same deviation occurs for two different angles of incidence because the path of light through the prism is symmetric.
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