The working principle of optical square is based on
- AReflection
- BRefraction
- CDouble reflectionCorrect
- DDouble refraction
Solution
Concept
Principle of the optical square
Step-by-step solution
1. An optical square has two mirrors inclined at 45°. 2. A ray reflected twice (double reflection) is deviated by twice the angle between the mirrors = 90°.
Explanation
The optical square works on the principle of double reflection. The angle between the first incident ray and the final reflected ray is 2 × 45° = 90°, which is used for setting out right angles.
Shortcut
Optical square: two mirrors at 45° → 90°.
Common mistake
Choosing reflection only.
Correct answer: C) Double reflection