Perputaran cermin
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.
Cara memakai simulasi ini
- Rotate the mirror through any angle
- Move the incident ray and change its direction
- Display the normal and the measured angles
Yang perlu diamati
- 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
Fisika di baliknya
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.