📚 IB Physics: A Guide to Experimental Work | IB 物理：实验操作指南
Experimental work is at the heart of IB Physics. It not only develops your practical skills but also reinforces theoretical concepts through hands-on investigation. Whether you are designing your Internal Assessment (IA) or performing prescribed practicals, a structured approach to experimentation will help you obtain reliable data, analyse it effectively, and present well-supported conclusions. This guide walks you through every stage of an IB physics experiment, from initial planning to final evaluation.
实验操作是 IB 物理的核心。它不仅能培养你的实践技能，还能通过动手探究强化理论知识。无论你是在设计内部评估（IA）还是完成规定实验，采用结构化的实验方法将有助你获得可靠数据、有效分析数据，并提出有充分依据的结论。本指南将带你走过 IB 物理实验的每一个阶段，从最初的规划到最终的评估。
1. Understanding the Scientific Method in IB Physics | 理解 IB 物理中的科学方法
The IB Physics course expects you to think and work like a scientist. This means formulating a clear research question, proposing a testable hypothesis based on prior knowledge, designing a procedure to test that hypothesis, collecting and analysing data, and then drawing conclusions that link back to the original question. The process is not linear; you may need to refine your method after initial trials.
IB 物理课程期望你像科学家一样思考和工作。这意味着你要提出清晰的研究问题，基于先验知识提出可检验的假设，设计检验该假设的实验步骤，收集并分析数据，然后得出与原始问题相关联的结论。这个过程不是线性的；你可能需要在初步尝试后改进自己的方法。
A strong experiment is built upon a focused question, for example: ‘How does the length of a pendulum affect its period?’ rather than a vague statement like ‘I want to study pendulums.’ The hypothesis should predict a specific relationship, such as ‘The period will increase as the square root of the length, following T = 2π√(L/g).’
一个优秀的实验建立在聚焦的问题上，例如：“单摆的长度如何影响其周期？”而不是模糊地说“我想研究单摆”。假设应预测具体的关系，例如“周期将随着长度的平方根增加，遵循 T = 2π√(L/g)”。
Always keep a logbook or digital record of your thoughts, preliminary observations, and any modifications you make. This transparency mirrors real scientific practice and is highly valued in IA assessment.
务必用实验记录本或电子记录保存你的想法、初步观察和所做的任何修改。这种透明度反映了真实的科学实践，在 IA 评估中很受重视。
2. Planning Your Experiment | 规划你的实验
Effective planning saves time and reduces errors. Begin by identifying the independent variable (the one you change), the dependent variable (the one you measure), and all variables that must be kept constant (control variables). List the apparatus you need, and sketch a diagram of your setup. This diagram should be labelled clearly, showing how instruments are arranged and where measurements are taken.
有效的规划能节省时间并减少错误。首先确定自变量（你改变的变量）、因变量（你测量的变量）以及所有必须保持不变的变量（控制变量）。列出你需要的仪器，并画出装置示意图。示意图应清晰标注，显示仪器如何布置以及在哪里进行测量。
Decide on the range of your independent variable and the number of data points. For a linear relationship, aim for at least six to eight different values spread over a wide range. Perform a trial run to see if your chosen range produces measurable and sensible changes in the dependent variable. Adjust your method if the changes are too small to detect or if the apparatus is not sensitive enough.
确定自变量的范围和数据点的数量。对于线性关系，至少选取六到八个分布范围广泛的不同数值。进行一次预实验，看看所选范围是否能在因变量中产生可测量且合理的变化。如果变化太小难以检测，或仪器不够灵敏，则需调整方法。
Risk assessment is essential. Identify any hazards (e.g., hot surfaces, sharp edges, falling masses) and state how you will minimize the risks. For IA, you must include a brief safety consideration.
风险评估至关重要。识别任何危险（例如，热表面、锋利边缘、坠落的砝码），并说明你将如何降低风险。对于 IA，你必须包含简短的安全考虑。
3. Variables and Controls | 变量与控制
In physics experiments, isolating the effect of one variable on another is key. The independent variable should be manipulated methodically. If you are investigating how the current through a resistor depends on voltage, voltage is the independent variable (set with a power supply) and current is the dependent variable (read from an ammeter).
在物理实验中，分离一个变量对另一个变量的影响是关键。自变量应系统地调控。如果你研究电阻中的电流如何取决于电压，那么电压是自变量（通过电源设置），电流是因变量（从安培表读出）。
Control variables must be monitored and maintained. For the resistor experiment, temperature is a control variable because resistance can change with temperature. You might keep the circuit on only when taking readings to avoid heating the resistor. Always state exactly how you will control each variable and with what instrument you will monitor it.
控制变量必须被监控和维持。在电阻实验中，温度是一个控制变量，因为电阻会随温度变化。你可以只在读数时接通电路，避免电阻发热。始终准确说明你将如何控制每个变量，以及你用什么仪器来监控它。
Sometimes a variable is difficult to control directly; in that case, you can monitor it and account for its effects. For example, atmospheric pressure might fluctuate, but if you record it alongside your main data, you can later assess its influence.
有时某个变量难以直接控制；在这种情况下，你可以监控它并考虑其影响。例如，大气压可能会波动，但如果你在记录主要数据的同时记录它，之后就可以评估它的影响。
4. Measurement Techniques and Instruments | 测量技术与仪器
Choosing the right instrument and using it correctly directly affects the quality of your data. Digital instruments like multimeters give a reading plus a ± error depending on the manufacturer’s specification. Analogue instruments such as rulers and analogue ammeters require you to estimate between the scale divisions; the uncertainty is typically half the smallest division.
选择正确的仪器并正确使用它直接影响数据的质量。数字仪器如万用表给出读数加上取决于制造商规格的 ± 误差。模拟仪器如直尺和模拟安培表要求你估计分度值之间的读数；不确定度通常是最小分度值的一半。
When measuring length, avoid parallax error by positioning your eye perpendicular to the scale. Use a set square to ensure the ruler is vertical or horizontal. For time measurements, human reaction time (around 0.2 s) is often the largest source of uncertainty; measure multiple oscillations and divide by the number of cycles to reduce this effect.
测量长度时，将视线垂直于刻度，避免视差误差。使用三角尺确保直尺垂直或水平。对于时间测量，人的反应时间（约 0.2 s）通常是最大的不确定度来源；测量多个振荡周期然后除以周期数以减小此影响。
Zero errors must be checked. For a micrometer screw gauge, close the jaws gently and see if the zero mark aligns; if not, subtract or add the zero error from all readings. Always mention whether you have accounted for zero errors in your report.
零误差必须检查。对于千分尺，轻合测砧，看零刻度是否对齐；如果没有，则从所有读数中减去或加上零误差。务必在报告中说明你是否已经考虑了零误差。
5. Data Collection and Recording | 数据收集与记录
Organise your data in a table before you start the experiment. The table should have clear headings with units and uncertainties. For example, a column for length might be headed ‘Length, L / cm (±0.1 cm)’. Record all raw data directly into the table; do not do mental calculations first. If you repeat a measurement, record every trial.
在开始实验前，将你的数据整理到一个表格中。表格应有清晰的标题，包含单位和不确定度。例如，长度列标题可写为“长度, L / cm (±0.1 cm)”。将所有原始数据直接记录到表中；不要先做心算。如果你重复测量，记录每一次试验。
Significant figures matter. Match the number of significant figures in your recorded data to the precision of the instrument. If a digital balance reads to 0.01 g, record ‘15.00 g’ not ’15 g’. Consistency in decimal places throughout a column reflects careful work.
有效数字很重要。将记录数据中的有效数字位数与仪器精度匹配。如果数字天平的读数为 0.01 g，记录“15.00 g”而不是“15 g”。整列小数位数的统一反映了严谨的工作。
Take multiple readings at each value of the independent variable – at least three, and more if time allows. This allows you to identify anomalies and calculate an average. If a reading looks clearly wrong (e.g., a spike due to a bumped table), you may exclude it but you must state the reason and record the original value.
对自变量的每一个值进行多次读数——至少三次，如果时间允许可以更多。这样你能识别异常值并计算平均值。如果某个读数明显错误（例如，由于桌子碰撞导致的尖峰），你可以将其排除，但必须说明理由并记录原始数值。
6. Uncertainty and Error Analysis | 不确定度与误差分析
Every measurement has uncertainty, and understanding how these uncertainties combine is a core skill. Distinguish between random and systematic errors. Random errors cause readings to scatter around the true value; they can be reduced by taking many measurements and averaging. Systematic errors shift all readings consistently, due to faulty equipment or flawed technique; they cannot be reduced by repetition.
每一个测量都有不确定度，理解这些不确定度如何组合是一项核心技能。区分随机误差和系统误差。随机误差导致读数围绕真值分散；可以通过多次测量取平均值来减小。系统误差由于仪器故障或有缺陷的操作方法而使所有读数一致偏移；不能通过重复来减小。
For a single measurement, the absolute uncertainty is often half the smallest division for analogue devices, or the manufacturer’s stated precision for digital ones. When you add or subtract quantities, add absolute uncertainties. When you multiply or divide, add percentage uncertainties. If a quantity is raised to a power, multiply the percentage uncertainty by that power.
对于单次测量，绝对不确定度通常取模拟仪器最小分度值的一半，或数字仪器厂家标明的精度。当你对物理量进行加减运算时，将绝对不确定度相加。当你进行乘除运算时，将百分比不确定度相加。如果一个量被乘方，将百分比不确定度乘以该幂次。
Propagate uncertainties through your data to find the uncertainty in the final result. For example, if you measure the diameter d of a wire and then calculate area A = π(d/2)², the percentage uncertainty in A is twice the percentage uncertainty in d. Show these calculations clearly in your report.
将不确定度传递到你的数据中，以找到最终结果的不确定度。例如，你测量导线直径 d 然后计算面积 A = π(d/2)²，那么 A 的百分比不确定度是 d 的百分比不确定度的两倍。在报告中清晰地展示这些计算。
7. Graphing and Linearization | 绘图与线性化
Graphs are powerful tools for identifying relationships. In IB Physics, you are expected to plot graphs by hand or with software, but you must understand how to linearise relationships. If the theory predicts y = k xⁿ, taking logarithms gives log y = n log x + log k, so a plot of log y against log x yields a straight line with gradient n. Alternatively, if you suspect a specific relationship like T = 2π√(L/g), you can square both sides to get T² = (4π²/g) L, and plot T² on the y-axis and L on the x-axis. The slope then equals 4π²/g, from which g can be calculated.
图表是识别关系的强大工具。在 IB 物理中，你需要用手工或软件绘制图表，但你必须理解如何将关系线性化。如果理论预测 y = k xⁿ，取对数得到 log y = n log x + log k，所以绘制 log y 对 log x 的图将得到一条斜率为 n 的直线。或者，如果你怀疑一个特定关系，如 T = 2π√(L/g)，你可以两边平方得到 T² = (4π²/g) L，并将 T² 放在 y 轴，L 放在 x 轴。那么斜率就等于 4π²/g，从中可以计算出 g。
T² = (4π²/g) L
When plotting, choose scales that use at least half the graph paper in each direction. Label axes with quantity and unit, such as ‘T² / s²’. Plot error bars if possible; for each point, show the uncertainty in the x and y directions using small lines. Draw a best-fit straight line or curve, and also plot lines of maximum and minimum slope (worst-fit lines) to determine the uncertainty in the gradient.
绘图时，选择每个方向至少使用坐标纸一半的刻度。用物理量和单位标注坐标轴，例如“T² / s²”。如果可能，绘制误差棒；对每个点，用短线段表示 x 和 y 方向的不确定度。画出最佳拟合直线或曲线，同时也画出最大和最小斜率线（最差拟合线），以确定斜率的不确定度。
8. Drawing Conclusions and Evaluation | 得出结论与评估
A conclusion must be based solely on the data you have collected, not on what you expected to find. Restate the relationship you have discovered, quote the mathematical expression with its constants and uncertainties, and compare it to the theoretical prediction. For example: ‘The experimental value of g was found to be (9.8 ± 0.3) m s⁻², which agrees with the accepted value of 9.81 m s⁻² within the experimental uncertainty.’
结论必须完全基于你收集的数据，而不是你期望发现的结果。重述你发现的关系，引用带常数和不确定度的数学表达式，并将其与理论预测进行比较。例如：“实验测得 g 值为 (9.8 ± 0.3) m s⁻²，在实验不确定度范围内与公认值 9.81 m s⁻² 一致。”
If there is a discrepancy, do not say ‘human error’ without explanation. Identify specific systematic or random errors that could have caused the difference. For instance, ‘the measured period was slightly too short because the oscillations had a significant amplitude, violating the small-angle approximation.’ Then suggest realistic improvements, such as using a more precise timing method or keeping the amplitude below 10°.
如果存在差异，不要不加解释地说“人为错误”。找出可能导致差异的具体系统误差或随机误差。例如，“测得的周期稍短，因为摆幅显著，违反了小角度近似”。然后提出切实可行的改进建议，例如使用更精确的计时方法或将振幅控制在 10° 以下。
Also evaluate the quality of your data. Comment on the spread of points about the best-fit line, the size of error bars, and whether your uncertainty calculations are realistic. A good evaluation shows critical thinking and awareness of the limitations of your experiment.
还要评估数据的质量。评论数据点相对于最佳拟合线的离散程度、误差棒的大小，以及你的不确定度计算是否现实。一个好的评估能体现批判性思维和对实验局限性的认识。
9. Common Pitfalls and How to Avoid Them | 常见误区及避免方法
Many students lose marks not because of difficult concepts but because of simple, avoidable mistakes. One common error is forgetting to measure the background or zero reading. For example, when using a radiation detector, you must measure the background count rate and subtract it from your readings.
许多学生丢分不是因为概念难，而是因为简单、可避免的错误。一个常见错误是忘记测量本底或零读数。例如，使用辐射探测器时，你必须测量本底计数率并从你的读数中减去它。
Another mistake is plotting a graph and then calculating the gradient using two data points instead of using the best-fit line. The best-fit line may not pass through any of your actual points, but it represents the optimal average relationship. Always take two points on the line of best fit that are far apart on the line for the gradient calculation.
另一个错误是绘制图表后，使用两个数据点而不是最佳拟合线来计算斜率。最佳拟合线可能不经过你的任何实际数据点，但它代表了最优的平均关系。始终在最佳拟合线上取两个相距较远的点来计算斜率。
Be careful with units. Convert all values to SI units before calculations unless the context requires otherwise. Inconsistency in units, such as mixing cm and m, will lead to large numerical errors. Double-check that your final result is expressed with the correct unit and to a reasonable number of significant figures.
注意单位。除非上下文另有要求，否则在计算前将所有数值转换为 SI 单位。单位不一致，例如混淆 cm 和 m，会导致很大的数值误差。仔细检查最终结果是否用正确的单位表达，并且有效数字位数合理。
10. IA-Specific Requirements | 内部评估的专门要求
The Internal Assessment is a single, complete investigation that you design and conduct. It is marked on five criteria: Personal Engagement, Exploration, Analysis, Evaluation, and Communication. Personal Engagement means showing initiative, creativity, and independent thinking. This could be demonstrated by designing your own method, adapting apparatus, or providing deep personal reflection on the learning process.
内部评估是一项由你自行设计和完成的完整探究。它根据五个标准评分：个人参与、探索、分析、评估和交流。个人参与意味着展现主动性、创造力和独立思维。这可以通过设计你自己的方法、改装仪器，或对学习过程进行深入的个人反思来体现。
Exploration requires a well-defined research question, a clear methodology, and addressing safety, environmental, and ethical considerations. Your raw data table, with all uncertainties and units, belongs here. The analysis section should show correct data processing, including uncertainty propagation, graph plotting, and mathematical interpretation. Do not include the raw data again in the analysis; refer back to the exploration section.
探索要求有明确的研究问题、清晰的方法，并涉及安全、环境和伦理考虑。包含所有不确定度和单位的原始数据表格应放在此部分。分析部分应展示正确的数据处理，包括不确定度传递、图表绘制和数学解释。不要将原始数据再次放入分析部分；应引用探索部分的表格。
Evaluation must go beyond a superficial ‘it went well’. Include a thorough discussion of strengths and weaknesses of your method, and suggest specific, effective improvements. The communication criterion assesses how clearly and logically your report is structured and written. Use consistent terminology, proper headings, and ensure any graphs are well-presented and fully labelled.
评估必须超越肤浅的“实验进行顺利”。要对方法的长处和弱点进行透彻讨论，并提出具体、有效的改进。交流标准评估你的报告结构和写作是否清晰、有逻辑。使用一致的术语、适当的标题，并确保所有图表呈现良好且标注完整。
11. Using Technology and Software | 使用技术和软件
While manual graph plotting is an important skill, IB allows and encourages the use of data-logging equipment and software such as Excel, Logger Pro, or Vernier Graphical Analysis. These tools can reduce random errors through fast sampling, and they make it easier to fit curves and calculate uncertainties. However, you must still understand the underlying mathematics. When using software for a linear fit, always display the equation of the line and the R² value, and state how you determined the uncertainty of the slope (often from standard error output).
虽然手工作图是一项重要技能，但 IB 允许并鼓励使用数据记录设备和软件，如 Excel、Logger Pro 或 Vernier Graphical Analysis。这些工具可以通过快速采样减少随机误差，并且使曲线拟合和不确定度计算更加容易。然而，你仍然必须理解背后的数学。当你使用软件进行线性拟合时，始终显示直线方程和 R² 值，并说明你是如何确定斜率的不确定度的（通常来自标准误差输出）。
Video analysis is another powerful technique. Recording a falling object or an oscillating system and then tracking its motion frame by frame can yield precise position-time data. This is excellent for IA projects exploring projectile motion or simple harmonic motion.
视频分析是另一种强大的技术。录制一个下落的物体或一个振荡系统，然后逐帧跟踪其运动，可以得到精确的位置-时间数据。这对于探索抛体运动或简谐运动的 IA 项目非常有利。
Remember that any electronic data must be clearly referenced in your report. Screenshots of data tables or graphs from software should be included in the appropriate sections, with axes still labelled and error bars shown if the software allows.
请记住，任何电子数据都必须在你报告中清晰引用。软件中的数据表格或图表的屏幕截图应包含在适当的章节中，坐标轴仍须标注，并且如果软件允许，应显示误差棒。
12. Final Checks and Presentation | 最终检查与呈现
Before submitting your practical report or IA, go through a checklist: Is the research question focused? Are all raw data tables complete with units and uncertainties? Have you shown sample calculations clearly, including one example of each type of uncertainty propagation? Are your graphs correctly scaled, titled, and do they include best-fit lines and worst-fit lines with gradient calculations? Does your conclusion explicitly refer back to the research question and the theory?
在提交你的实验报告或 IA 之前，过一遍核查清单：研究问题是否聚焦？所有原始数据表是否完整，包含单位和不确定度？是否清晰地展示了样本计算，包括每种不确定度传递类型的一个例子？你的图表缩放正确、有标题，并且包含最佳拟合线和最差拟合线以及斜率计算吗？你的结论是否明确地回引了研究问题和理论？
Proofread for clarity and consistency. Avoid using the first person unless it genuinely adds to personal engagement; ‘the length was measured’ is often better than ‘I measured the length’. Ensure all terms like ‘uncertainty’, ‘error’, and ‘precision’ are used correctly. A well-presented report demonstrates care and scientific maturity, which can enhance your overall grade.
校阅以确保清晰和一致。除非确实能增加个人参与感，否则避免使用第一人称；“测量了长度”通常比“我测量了长度”更好。确保“不确定度”、“误差”、“精度”等术语使用正确。一份呈现良好的报告展示了严谨的科学素养，这可以提升你的整体成绩。
Published by TutorHao | Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导Cancel reply