Question

Under what condition in an arrangement of two plane mirrors, incident ray and reflected ray will always be parallel to each other ?

• A. When two plane mirrors are placed at right angle to each other.
• B. When two plane mirrors are placed parallel to each other.
• C. When two plane mirrors are placed at ${30}^0$ angle to each other.
• D. When two plane mirrors are placed at ${60}^0$ angle to each other.

Answer 1

The correct option is A When two plane mirrors are placed at right angle to each other.

When two plane mirrors are placed perpendicular to each other. angle between incident ray and reflected ray $=2i$ angle between second incident ray and reflected ray $={180}^0-2i$ sum of the angle $={180}^0$ hence,the reflected ray is parallel to incident ray.