Consider a light ray reflected from a mirror. If the mirror is rotated by an angle of 45 degrees, the reflected ray will change its orientation by an angle of ______.
Consider a light ray reflected from a mirror. If the mirror is rotated by an angle of 45 degrees, the reflected ray will change its orientation by an angle of ______.
The correct option is B 90 degrees
In the 1st figure, let us suppose that a light ray is incident at an angle α to a mirror. As per the law of reflection, the reflected ray makes an angle α with the normal OX.
In the 2nd figure, the mirror is tilted at an angle θ. As the mirror is tilted, the normal will also tilt by the same angle ( blue line). The same incident light ray now makes an angle θ+α with the new normal . As per the law of reflection, the new reflected ray OY (indicated with green line) makes an angle θ+α with the normal. From the figure , we can observe that the new reflected ray (green line) makes an angle 2θ+α with the old normal OX.
Hence the change of angle is 2θ.
Here, the mirror is rotated by θ=45∘. Hence the reflected ray will change its orientation by 2θ=90∘.
90 degrees
In the 1st figure, let us suppose that a light ray is incident at an angle α to a mirror. As per the law of reflection, the reflected ray makes an angle α with the normal OX.
In the 2nd figure, the mirror is tilted at an angle θ. As the mirror is tilted, the normal will also tilt by the same angle ( blue line). The same incident light ray now makes an angle θ+α with the new normal . As per the law of reflection, the new reflected ray OY (indicated with green line) makes an angle θ+α with the normal. From the figure , we can observe that the new reflected ray (green line) makes an angle 2θ+α with the old normal OX.
Hence the change of angle is 2θ.
Here, the mirror is rotated by θ=45∘. Hence the reflected ray will change its orientation by 2θ=90∘.
