A-Level Physics Unit 3 Mark Scheme Jan19: Mastering Experimental Inquiry | A-Level 物理 Unit 3 评分方案 2019年1月：掌握实验探究

📚 A-Level Physics Unit 3 Mark Scheme Jan19: Mastering Experimental Inquiry | A-Level 物理 Unit 3 评分方案 2019年1月：掌握实验探究

The A-Level Physics Unit 3 paper assesses practical skills through written questions on experimental planning, data analysis, and evaluation. The January 2019 mark scheme reveals the precise criteria examiners use to award marks. This article unpacks those criteria, offering a bilingual guide to mastering experimental inquiry—from controlling variables to calculating uncertainties. Whether you are revising for Edexcel or another board, the principles discussed here will sharpen your exam technique.

A-Level 物理单元 3 考试通过书面题目评估实验技能，涉及实验规划、数据分析和评估。2019 年 1 月的评分方案揭示了考官评分的确切标准。本文解读这些标准，提供一份掌握实验探究的双语指南——从控制变量到计算不确定度。无论你正在备考 Edexcel 还是其他考试局，此处讨论的原则都将提升你的应试技巧。

1. Understanding the Structure of Unit 3 | 理解单元3的结构

Unit 3 typically consists of structured questions based on experimental scenarios provided in the paper. You may be asked to plan an investigation, complete a table of results, plot a graph, or evaluate the procedure.

单元 3 通常由基于试卷给出的实验情境的结构化问题组成。你可能需要设计一项调查、完成结果表格、绘制图表或评估实验步骤。

The mark scheme for January 2019 shows that marks are allocated for specific skills: identifying variables, naming appropriate apparatus, recording readings with correct precision, plotting points accurately, drawing a best-fit line, calculating gradients, determining uncertainties, and suggesting valid improvements. Each mark corresponds to a demonstrable skill.

2019 年 1 月的评分方案显示，分数分配给特定技能：识别变量、命名合适仪器、以正确精度记录读数、准确描点、绘制最佳拟合线、计算斜率、确定不确定度以及提出有效的改进建议。每一分都对应一项可展示的技能。

Furthermore, the paper often includes a question that requires you to explain why a particular piece of apparatus is chosen. The mark scheme expects you to link the apparatus to its resolution and how it reduces a specific uncertainty.

此外，试卷常包含一道要求解释为何选用某种特定仪器的问题。评分方案期望你将仪器与其分辨率联系起来，并说明它如何减小某一具体的不确定度。

2. Planning an Experiment: Variables and Controls | 规划实验：变量与控制

Every experiment begins with a clear aim. You must state the independent variable (the one you deliberately change), the dependent variable (the one you measure), and all control variables that could affect the outcome.

每个实验都始于明确的目标。你必须陈述自变量（你故意改变的变量）、因变量（你测量的变量）以及所有可能影响结果的控制变量。

For example, in an investigation of how the length of a wire affects its resistance, length is the independent variable, resistance is the dependent variable, and temperature, wire material, and cross‑sectional area must be kept constant. The mark scheme often rewards explicit statements of how you will keep each control variable constant—e.g., “use the same wire throughout” or “allow the wire to cool between readings.”

例如，在研究导线长度如何影响电阻的实验中，长度是自变量，电阻是因变量，温度、导线材料和横截面积必须保持不变。评分方案通常奖励明确说明如何保持每个控制变量不变的表述——例如”始终使用同一根导线”或”在读数之间让导线冷却”。

If a control variable is not kept constant, the relationship between the independent and dependent variables may be masked, and the results will lack reliability. The Jan19 mark scheme penalised vague statements such as “keep everything the same” and demanded specific, practical actions.

如果控制变量未能保持不变，自变量与因变量之间的关系可能被掩盖，结果将缺乏可靠性。2019 年 1 月的评分方案对”让所有东西都一样”之类模糊的表述进行了扣分，要求给出具体、实际的措施。

3. Recording Data with Precision and Accuracy | 精确与准确地记录数据

When taking measurements, always record the resolution of the instrument and estimate the uncertainty. For a metre ruler, the resolution is 1 mm, so each reading has an absolute uncertainty of ±0.5 mm. The January 2019 paper expected candidates to state readings to the nearest half‑division.

在测量时，务必记录仪器的分辨率并估计不确定度。对于米尺，分辨率为 1 mm，因此每个读数的绝对不确定度为 ±0.5 mm。2019 年 1 月的试卷要求考生将读数记录到最接近的半格。

Repeat readings are essential to reduce random error. Calculate the mean of repeated values and identify any anomalous results that deviate significantly from the pattern. The mark scheme may ask you to circle an anomalous point and explain why it should be excluded.

重复读数对于减小偶然误差至关重要。计算重复值的平均值，并识别任何明显偏离模式的异常结果。评分方案可能会要求你圈出一个异常点并解释为何应将其排除。

The key rule is to record all raw data to the same number of decimal places, matching the instrument’s precision

Published by TutorHao | A-Level Physics Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）