Reflection
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课程笔记
Key Facts about Light
- Light is a transverse wave.
- Transverse waves have vibrations perpendicular to the direction of wave travel.
- Light travels at 300 000 000 m/s (the speed of light).
- Light is part of the electromagnetic spectrum, which contains seven types of transverse waves.
Specular Reflection
- Specular reflection occurs when light reflects from a very smooth surface, like a mirror.
- The incident ray is the ray approaching the surface.
- The normal is an imaginary line drawn at 90° to the surface.
- The angle of incidence is the angle between the incident ray and the normal.
- The reflected ray leaves the surface; its angle with the normal is the angle of reflection.
- The law of reflection states: angle of incidence = angle of reflection.
Diffuse Reflection
- Diffuse reflection happens when light reflects from a rough surface.
- Rays are reflected at many different angles because the surface is uneven.
- The law of reflection still holds for each individual ray (angle i = angle r).
- The overall effect is that the reflected light is scattered, not focused.
The Law of Reflection
- The law of reflection applies to all waves, not just light.
- It can be stated as: angle of incidence = angle of reflection.
- Both angles are measured from the normal, not from the surface.
Specular reflection showing incident ray, reflected ray, normal, and equal angles of incidence and reflection.
幻灯片
练习题
免费预览——64 题中的 8 题。注册即可查看全部。
1.Which of the following best describes light?
Easy- AA transverse wave
- BA longitudinal wave
- CA stationary wave
- DA mechanical wave
2.What is the speed of light?
Easy- A300 000 000 m/s
- B300 000 m/s
- C3 000 000 m/s
- D30 000 000 m/s
3.The law of reflection states that:
Easy- AThe angle of incidence equals the angle of reflection.
- BThe angle of incidence is greater than the angle of reflection.
- CThe angle of incidence is less than the angle of reflection.
- DThe angle of incidence is measured from the mirror surface.
4.Which type of reflection occurs when light hits a rough surface?
Easy- ADiffuse reflection
- BSpecular reflection
- CTotal internal reflection
- DRegular reflection
5.In a specular reflection, the reflected rays are:
Easy- AParallel to each other
- BScattered in many directions
- CAbsorbed by the surface
- DRefracted into the surface
6.What is the normal in a ray diagram?
Easy- AA line drawn at 90° to the mirror
- BThe incident ray
- CThe reflected ray
- DThe mirror surface
7.Which of the following is true about diffuse reflection?
Medium- AThe angle of incidence is still equal to the angle of reflection for each ray.
- BThe angle of incidence is not equal to the angle of reflection.
- CThe law of reflection does not apply.
- DThe surface is very smooth.
8.Which of the following waves obey the law of reflection?
Easy- ALight waves only
- BAll waves
- COnly transverse waves
- DOnly electromagnetic waves
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