AS Physics Unit 2 June 2019 Experimental Question Analysis | AS物理：单元2 2019年6月实验题解析

📚 AS Physics Unit 2 June 2019 Experimental Question Analysis | AS物理：单元2 2019年6月实验题解析

In the June 2019 AS Physics Unit 2 examination, the experimental question challenged students to demonstrate a thorough understanding of practical physics. A typical task involved determining the resistivity of a metal wire by measuring its resistance, length and diameter, and then critically evaluating the uncertainties involved. This article provides a detailed walkthrough of such an investigation, highlighting the key skills needed to gain full marks.

在2019年6月的AS物理单元2考试中，实验探究题要求学生展现出对实践物理的透彻理解。一个典型的题目是通过测量导线的电阻、长度和直径来确定导线的电阻率，然后对涉及的不确定度做出批判性评估。本文将对这一探究过程进行详细解析，突出获得满分所需的关键技能。

1. Experiment Objective and Context | 实验目标与背景

The core aim was to calculate the resistivity ρ of a given metal wire using the relationship ρ = RA/L, where R is resistance, A is cross-sectional area and L is length.

核心目标是利用关系式 ρ = RA/L 计算给定金属导线的电阻率ρ，其中R是电阻，A是横截面积，L是长度。

Resistivity is a fundamental material property that dictates how strongly a material opposes current flow. The experimental approach involves an independent variable (length of wire), a dependent variable (resistance), and several control variables (temperature, wire material, cross-sectional area).

电阻率是一个基本的材料属性，决定了材料阻碍电流流动的强弱程度。实验方法涉及自变量（导线长度）、因变量（电阻）以及多个控制变量（温度、导线材料、横截面积）。

In the 2019 paper, a circuit diagram was provided, and students were expected to record pairs of potential difference (p.d.) V and current I for different wire lengths placed in the circuit.

在2019年的试卷中给出了电路图，学生需要记录电路中使用不同长度导线时的电势差V和电流I的对应数据。

Key physics: For a uniform wire at constant temperature, resistance is directly proportional to length, so a graph of R against L yields a straight line through the origin.

关键物理：对于均匀导线在恒温条件下，电阻与长度成正比，因此R-L图将是一条通过原点的直线。

2. Identifying Variables and Apparatus | 识别变量与实验仪器

A successful investigation begins with a clear identification of the independent, dependent and controlled variables. The independent variable is the length of the wire L, altered by moving a crocodile clip along a metre ruler.

成功的探究始于明确识别自变量、因变量和控制变量。自变量是导线长度L，通过沿米尺移动鳄鱼夹来改变。

The dependent variable is the resistance R, which is derived from the ratio V/I obtained from voltmeter and ammeter readings.

因变量是电阻R，通过伏特计和安培计的读数计算比值V/I得出。

Controlled variables include the temperature (keep current small to avoid heating), the wire material (same wire throughout

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