Rotação de um espelho
Rotate a mirror by ten degrees and the reflected ray swings by twenty. This simulation makes that factor-of-two relationship visible by letting you turn the mirror while the incident ray stays fixed, tracking both angles as you go.
Como usar esta simulação
- Rotate the mirror through any angle
- Move the incident ray and change its direction
- Display the normal and the measured angles
O que observar
- The reflected ray turns through twice the mirror's rotation
- Angle of incidence always equals angle of reflection, however the mirror is placed
- Keeping the mirror fixed and moving the source changes both angles together
A física por trás
The law of reflection fixes the angle of reflection equal to the angle of incidence, both measured from the normal. Rotating the mirror by an angle θ also rotates the normal by θ, which changes the angle of incidence by θ and the angle of reflection by θ in the same sense — so the reflected ray turns through 2θ. This doubling is the basis of the optical lever used in sensitive instruments.