Waves and optics · 波动与光学
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| diffraction/dɪˈfrækʃn/ | 衍射 | yǎn shè |
| coherence/kəʊˈhɪərəns/ | 相干性 | xiāng gān xìng |
A decision before an answer
- Two individually bright waves can cancel at a point if their phases oppose.
- Your goal: Analyse wave superposition and interference.
答案前的判断
- 两列各自明亮的波若在特定点相位相反，则可能相互抵消。
- 你的目标：分析波的叠加与干涉。
Read the relationship
- Add wave amplitudes, then calculate intensity. Intensity is proportional to squared amplitude for the same medium.
- Use diffraction, polarisation and optical imaging.
阅读关系
- 先叠加波振幅，再计算强度。对于同一介质，强度正比于振幅的平方。
- 运用衍射、偏振和光学成像。
Doubling wavelength at fixed slit width makes the first minimum angle:
sin θ=λ/a increases.
Use the defining rule
- A path difference gives phase difference 2πΔ/λ. Coherent sources need stable relative phase.
- Relate phase, frequency and dispersion.
运用定义规则
- 光程差导致相位差 2πΔ/λ。相干光源需要稳定的相对相位。
- 关联相位、频率和色散。
An ideal polariser transmits unpolarised intensity I as:
Averaging the squared projection gives half.
Check the conditions
- For a single slit, minima satisfy a sin θ=mλ for nonzero integers m. A double slit has a different interference condition.
- Relate phase, frequency and dispersion.
Two equal coherent waves have amplitude A each. In phase, their total amplitude is 2A and intensity is 4I₀. With phase difference π, amplitude and ideal intensity are zero. Adding intensities directly misses interference.
检查条件
- 单缝衍射极小值满足 a sin θ=mλ（m为非零整数）。双缝干涉条件不同。
- 关联相位、频率和色散。
两列等幅相干波振幅均为A。同相时总振幅为 2A，强度为 4I₀。若存在π的相位差，振幅及理想强度均为零。直接相加强度会忽略干涉效应。
For frequency 5 Hz and wavelength 2 m, wave speed is ____ m/s.
v=fλ=5×2=10.
Apply the task format
- Geometric optics needs a stated sign convention. Wave effects matter when apertures are comparable to wavelength.
- Relate phase, frequency and dispersion.
The central single-slit maximum is not obtained by setting m=0 in the minima condition.
应用题目格式
- 几何光学需明确符号约定。当孔径与波长可比拟时，波动效应显著。
- 关联相位、频率和色散。
中央单缝极大值并非通过令 m=0 代入极小值条件得出。
Which answer fits this case? · 哪个答案符合此案例？
Analyse wave superposition and interference · 分析波的叠加与干涉
Wave intensities can always be added without considering phase.
Coherent waves interfere through amplitude addition.
Keep the distinctions
- coherence 相干性 — A stable phase relationship between waves.
- diffraction 衍射 — Wave spreading and interference caused by an aperture or obstacle.
- Analyse wave superposition and interference.
- Use diffraction, polarisation and optical imaging.
- Relate phase, frequency and dispersion.
保持区别
- coherence 相干性 — 波之间稳定的相位关系。
- diffraction 衍射 — 由孔径或障碍物引起的波扩散与干涉现象。
- 分析波的叠加与干涉。
- 运用衍射、偏振和光学成像。
- 关联相位、频率和色散。
Match each term with its precise meaning in this lesson.
Keep the distinctions stated in the teaching example.
Put this lesson’s reasoning or event sequence in order.
The order follows the stated process; check each stage before the next.