Physics - Geometrical Optics Question with Solution | TestHub
In the figure shown a thin parallel beam of light is incident on a plane mirror m1 at small angle ‘q’. m2 is a concave mirror of focal length ‘f’. After three successive reflections of this beam the x and y coordinates of the image is
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Solution:
Solution:
Let the incident beam be parallel to the x-axis.
1. First reflection (M₁): The beam reflects at an angle with the normal. The reflected ray makes an angle with the incident direction.
2. Second reflection (M₂): The ray hits the concave mirror M₂. Since the incident ray passes through the focus, it reflects parallel to the principal axis.
3. Third reflection (M₁): The ray reflects off M₁ again. The final image is formed at a distance from M₂.
The final image coordinates are and .
The incident ray is parallel to the x-axis, so its initial y-coordinate is .
After the first reflection from M₁, the ray makes an angle with the x-axis.
The concave mirror M₂ is placed at .
The focal length of M₂ is .
The incident ray on M₂ is parallel to the principal axis (x-axis) after the second reflection.
The final image is formed at a distance from M₂.
The x-coordinate of the image is .
The y-coordinate of the image is (due to the small angle approximation and the reflection from M₁).
The final answer is .