📚 Hypothesis: A Guide for AQA A-Level Physics | 假设：AQA A-Level 物理指南
In AQA A-Level Physics, a hypothesis is more than an educated guess. It is a proposed explanation for an observation or a predicted relationship between variables, written so that it can be tested by experiment. Understanding how to formulate and evaluate a hypothesis is essential for practical assessments, the required practicals, and data-analysis questions.
在 AQA A-Level 物理中，假设不仅仅是基于知识的猜测。它是对观察现象提出的解释，或对变量之间关系的预测，并以能够通过实验检验的方式表述。理解如何提出和评估假设对实验评估、必修实验和数据分析题都至关重要。
1. What Is a Hypothesis? | 什么是假设？
A hypothesis is a clear, testable statement that proposes a possible explanation for a phenomenon or a relationship between an independent variable and a dependent variable. In physics, it often takes the form 'If the independent variable changes in a certain way, the dependent variable will respond in a specific way because of a stated mechanism.'
假设是一种清晰、可检验的陈述，提出对某一现象的可能解释，或自变量与因变量之间的某种关系。在物理中，假设常写成 '如果自变量以某种方式变化，因变量就会以特定方式响应，因为存在某种说明的机制'。
For example, for a metallic wire at constant temperature, a hypothesis could be: 'If the potential difference across the wire is increased, the current will increase proportionally because the resistance remains constant.' This is testable, measurable and based on Ohm's law.
例如，对于恒温下的金属导线，假设可以写成：'如果增大导线两端的电势差，电流就会成正比增大，因为电阻保持不变'。这一假设可检验、可测量，并基于欧姆定律。
2. Hypothesis vs Prediction | 假设与预测的区别
Students often confuse a hypothesis with a prediction. A hypothesis proposes an explanation or a causal link, while a prediction is the specific measurable outcome you expect to observe if the hypothesis is correct. For example, the hypothesis might be that a pendulum's period depends on its length; the prediction would be that doubling the length increases the period by a factor of about √2.
学生常把假设与预测混淆。假设提出一种解释或因果联系，而预测是如果假设正确，你预期观察到的具体可测量结果。例如，假设可能是单摆的周期取决于摆长；预测则是摆长加倍时，周期增大约 √2 倍。
T = 2π√L/g
The equation T = 2π√L/g supports the prediction: when L is multiplied by 2, T should become √2 times larger if g is constant.
公式 T = 2π√L/g 支持该预测：当 L 乘以 2 时，如果 g 不变，T 应变为原来的 √2 倍。
3. The Role of a Hypothesis in Physics | 假设在物理中的作用
In physics, a hypothesis provides a starting point for designing an experiment. It identifies the variables to be measured and suggests the expected relationship, allowing the experimenter to plan appropriate apparatus, range, and repeats.
在物理中，假设为设计实验提供起点。它确定了要测量的变量，并给出预期的关系，使实验者能够规划合适的装置、测量范围和重复次数。
A good hypothesis also guides data analysis. If the results do not support the hypothesis, the experimenter must consider systematic or random errors, limitations of the model, or whether the hypothesis should be rejected or modified.
一个好的假设还能指导数据分析。如果结果不支持假设，实验者需要考虑系统误差或随机误差、模型的局限性，或者是否应拒绝或修改假设。
4. Features of a Testable Hypothesis | 可检验假设的特征
A testable hypothesis must be specific, measurable, falsifiable and based on sound physics. Saying 'the resistance changes with length' is too vague because it does not state the direction or mechanism. A better version is: 'As the length of a wire increases, its resistance increases proportionally because there are more lattice ions for electrons to collide with.'
可检验的假设必须具体、可测量、可证伪，并基于可靠的物理原理。只说 '电阻随长度变化' 过于模糊，因为没有说明方向或机制。更好的版本是：'随着导线长度增加，其电阻成正比增大，因为电子与晶格离子碰撞的机会增多'。
Falsifiability means there must be a possible outcome that would show the hypothesis is wrong. If every possible result can be explained by the hypothesis, it is not scientifically useful.
可证伪性意味着必须存在一种可能的结果，能够表明假设是错的。如果每一种可能结果都能用该假设解释，那么这个假设在科学上没有用处。
5. Formulating a Hypothesis | 如何提出假设
To formulate a hypothesis, start with a research question, identify the independent and dependent variables, and state the expected relationship with a reason. A common structure is: 'If the independent variable is changed by ..., the dependent variable will ... because ...'.
要提出假设，先从研究问题入手，确定自变量和因变量，然后陈述预期的关系并给出理由。常见的结构是：'如果自变量改变……，那么因变量将……，因为……'。
For example, in an experiment to investigate the extension of a spring, a hypothesis could be: 'If the force applied to a spring is increased, the extension will increase proportionally, because the spring obeys Hooke's law within its elastic limit.'
例如，在研究弹簧伸长量的实验中，假设可以写成：'如果施加在弹簧上的力增大，伸长量将成正比增大，因为在弹性限度内弹簧遵循胡克定律'。
6. Variables and the Hypothesis | 变量与假设
A hypothesis must make clear which variable is changed, which variable is measured, and which variables are kept constant. These are the independent variable, the dependent variable and the control variables.
假设必须明确哪个变量被改变、哪个变量被测量、哪些变量保持不变。它们分别是自变量、因变量和控制变量。
In the wire-resistance experiment, the independent variable is wire length, the dependent variable is resistance, and control variables include temperature, cross-sectional area and material. The hypothesis should focus on the relationship between length and resistance while implying that controls are held constant.
在导线电阻实验中，自变量是导线长度，因变量是电阻，控制变量包括温度、横截面积和材料。假设应聚焦于长度与电阻的关系，并暗示控制变量保持不变。
7. Testing a Hypothesis Experimentally | 通过实验检验假设
Testing a hypothesis requires a fair test. Only the independent variable should be changed, the dependent variable should be measured with appropriate precision, and control variables must be monitored. Repeats and averages reduce random error, while calibration and zero checks reduce systematic error.
检验假设需要公平实验。只能改变自变量，因变量应以适当精度测量，控制变量必须得到监控。重复测量和取平均值可以减小随机误差，而校准和零点检查可以减小系统误差。
After collecting data, plot a graph. If the hypothesis predicts a proportional relationship, a straight line through the origin supports it. If the graph is curved or does not pass through the origin, the hypothesis may need to be rejected or revised.
收集数据后，绘制图像。如果假设预测成正比关系，则一条过原点的直线支持该假设。如果图像是曲线或不过原点，假设可能需要被拒绝或修正。
8. Hypothesis, Theory and Law | 假设、理论和定律
In physics language, a hypothesis is an initial testable idea. If a hypothesis is supported by a large body of experimental evidence, it may become a theory, which provides a broad explanation. A law is a concise mathematical statement of a repeated pattern, such as Ohm's law or Hooke's law, without necessarily explaining the underlying cause.
在物理语言中，假设是初步的可检验想法。如果假设得到大量实验证据的支持，它可能成为理论，提供更广泛的解释。定律是对重复出现的模式的简洁数学陈述，如欧姆定律或胡克定律，但不一定解释其根本原因。
For example, the hypothesis that current is proportional to potential difference for a metallic conductor at constant temperature was tested repeatedly and became part of Ohm's law. The law does not explain why resistance exists; the theory of electron-ion collisions provides the explanation.
例如，在恒温下金属导体中电流与电势差成正比的假设经过反复检验，成为欧姆定律的一部分。该定律并不解释电阻为何存在；电子-离子碰撞理论提供了这一解释。
9. Common Mistakes in Hypothesis Writing | 写假设的常见错误
A common mistake is writing a hypothesis as a question. A hypothesis must be a statement, not 'What happens to the period if the length changes?'. Another mistake is using vague terms like 'affects' without stating the direction or relationship.
一个常见错误是把假设写成问句。假设必须是陈述句，而不是 '长度改变时周期会怎样？'。另一个错误是使用 '影响' 等模糊词语，却没有说明方向或关系。
Some students write a prediction without a mechanism, such as 'the period will increase', but this lacks the 'because' element. Others describe how to do the experiment instead of stating the expected relationship. Keep the hypothesis about the physics, not the procedure.
有些学生只写预测而没有机制，例如 '周期将增大'，但缺少 '因为' 部分。还有些学生写的是如何做实验，而不是陈述预期关系。假设应关注物理，而不是操作步骤。
10. Hypothesis in AQA Practical Questions | AQA 实验题中的假设
In AQA practical-based questions, you may be asked to suggest a hypothesis for a given scenario, or to evaluate whether data supports a stated hypothesis. Use the 'If ... then ... because ...' structure and link the explanation to the relevant physics principle.
在 AQA 实验题中，你可能需要针对给定情境提出假设，或评估数据是否支持某一陈述的假设。使用 '如果……那么……因为……' 的结构，并将解释与相关物理原理联系起来。
For example, if a question asks you to investigate how the acceleration
Published by TutorHao | A-Level Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图