Question

two mirrors are kept perpendicular to each other . a ray strikes one mirror at an angle of 45 degree to the normal find the direction of the ray after reflection by the second mirror by drawing a ray diagram

Answer 1

in the diagram AB is the incident ray and the mirror are perpendicular to each other. Therefore CD is the reflected ray

Tip : no used to measure the angles and make

Answer 2

The ray diagram for the problem statement is shown in the image below. Final reflected ray is in a direction parallel to the incident ray.

From the figure:

• MN and PQ are the two normal drawn on both mirrors at the point of incidence.
• AO and BO are perpendicularly placed.
• CR is the incident ray for mirror AO and it makes an angle of 45 degrees with the normal.
• RS is the reflected ray for mirror AO and incident ray for mirror BO.
• According to law of reflection, angle of incidence is equal to the angle of reflection.
• So, ∠CRN = ∠NRS = 45°

In ΔROS:

• ∠ORS = 45°
• So from the law of triangle, sum of all angles of a triangle is equal to 180°.
• Therefore, ∠RSO = 45°
• Now, ∠RSP = 45° is angle of incidence for mirror OB. So, angle of reflection for mirror OB = ∠PSD = 45°

Rays CR and DS are parallel to each because the interior angles are equal.

∠RSD = ∠CRS = 90°, so final reflected ray and incident ray are parallel.